First, the third option is something made the worlds like that intentionally for some reason (experiment, the planetary spirits are holding that position so some other entity is removed from the game, precursor race's long term anthropological experiment, etc...). Even if this is religious mythonly it should still be important, pre-second world colonization we are talking about a biosphere that can be seen with a telescope. Its real hard to argue against life on other planets when you can actually disprove that by pointing at the nearest celestial body. Even if its as recent as the stories developing as of the end of the last war, people are going to talk about the other planet itself as if it was an evil God. Perhaps going as far as declaring the other planet Hell manifest... generally things devolve into seeing conquering the other world as a religious obligation to conquer hell for whatever their cause actually is.
Without tides I'm not sure anyone would actually build coastal cities of note. River straddling cities sure... but without a tide all the garbage and sewage dumped into the sea will just sit there. Rivers would end up as symbols of life (and/or the path/cycle there of), movement, and good things... stagnant oceans the opposite. Actually, if the post armagedon peoples see the sky world as hell then the stagnant oceans would be the the underworld you want to go to. Burial by floating them down river into the seas. I realize there will be currents... but without a regular tide the shore line will end up a field of algae and seaweeds. Add in something big and air breathing feeding in these coasts and no one will want to go in the sea. Something that is big mostly because of all the food near shore. Something that attacks boats so they just never decided that it was work exploring the oceans and sea on the water. Until flight comes around anyway.
This means only one major (or major heavily colonized/populated) land mass on at least first world. Till flight no one would want to attempt crossing the death field out there... would also mean any rocket style flight or dangerous labs would be on the previously undeveloped other, smaller land masses. That way you don't screw up the land you live on and don't have tourists. This also gives you a way that the two planets can actually assault each other. The fringe labs and installations had enough bunker type installations they were more or less intact post bombardment. Its just with no incoming resources they are going to take far longer to get to the central land mass or set up harvesting operations. Besides being outsiders in the fringes of the planet anyway those central landmass morons blew up the worlds.
So we have tech surviving in the worlds in small groups. give them a few decades to organize and they can set up a ferry service for iron ageish war parties. Have them do this for both planets (in different ships designs) and demand tribute and you can have a nice little racket going. Keep it to a few raids a year and maybe get it in the yokels heads that surviving a raid is a manhood/ rite of passage thing... advance a few decades or centuries and iron age gets up to gunpowder age. By that point the ferrymen get some explitive of a leader, who pushes volume over safety and/or who starts demanding a desirable mate as payment from the war party (at first in loot and then in advance)... or irrational cuts of the haul or something. Eventually a few shuttles on both planets are downed and the locals make like those Africans in Lord of War and by the time the recovery team get ther its little more than a skeleton.
Cue enterprising nobles paying for this stuff and insert a nice boost to research and tech levels. Eventually someone makes radios... then radios good enough to taunt the other planet. Which eventually leads to both sides noting their respective ferrymen had undesirable price increase / spontaneous upswings in equipment failures at the same exact time. Cue both sides deciding its time to cut out the middle men. One war pair of wars later and you have your set up as both side attempt to figure out space flight on their own... the hold up may be the controls are so convoluted that 85% of them may only cause random lights to turn on and off and blink and flash... and the wiring is spaghetti logic.
Another reason for this landmass model is that your going to have one hell of a time running an iron age society on a global level if your constantly needing a navy and ocean crossing to communicate. With one major landmass you can set a nation up that way... remember your insisting that post war and a few hundred years after the fall they are maintaining military against each other and there are only two societies are actually worth uplifting on two planets. I find it entirely suspect that both world would count it as a good idea to reestablish mutual global governments at the same time anyway... unless the societies are just rigged to function that way. In which case they may have ended up nuking each other simply as a matter of deciding where the capital should be getting completely out of hand and the scientists not winning the race to build a capital city space station exactly between the two worlds. Something about actually researching how to make such a things and the implementation process taking longer that drunk (on power or booze), screaming politicians can order buttons to be pressed.
Just the first thing that came to my mind... but the main thing to remember is that if something as odd as two planets in exact tide killing orbit with each other is the basis of things... that will effect everything eventually.
Without tides I'm not sure anyone would actually build coastal cities of note. River straddling cities sure... but without a tide all the garbage and sewage dumped into the sea will just sit there. Rivers would end up as symbols of life (and/or the path/cycle there of), movement, and good things... stagnant oceans the opposite. Actually, if the post armagedon peoples see the sky world as hell then the stagnant oceans would be the the underworld you want to go to. Burial by floating them down river into the seas. I realize there will be currents... but without a regular tide the shore line will end up a field of algae and seaweeds. Add in something big and air breathing feeding in these coasts and no one will want to go in the sea. Something that is big mostly because of all the food near shore. Something that attacks boats so they just never decided that it was work exploring the oceans and sea on the water. Until flight comes around anyway.
This means only one major (or major heavily colonized/populated) land mass on at least first world. Till flight no one would want to attempt crossing the death field out there... would also mean any rocket style flight or dangerous labs would be on the previously undeveloped other, smaller land masses. That way you don't screw up the land you live on and don't have tourists. This also gives you a way that the two planets can actually assault each other. The fringe labs and installations had enough bunker type installations they were more or less intact post bombardment. Its just with no incoming resources they are going to take far longer to get to the central land mass or set up harvesting operations. Besides being outsiders in the fringes of the planet anyway those central landmass morons blew up the worlds.
So we have tech surviving in the worlds in small groups. give them a few decades to organize and they can set up a ferry service for iron ageish war parties. Have them do this for both planets (in different ships designs) and demand tribute and you can have a nice little racket going. Keep it to a few raids a year and maybe get it in the yokels heads that surviving a raid is a manhood/ rite of passage thing... advance a few decades or centuries and iron age gets up to gunpowder age. By that point the ferrymen get some explitive of a leader, who pushes volume over safety and/or who starts demanding a desirable mate as payment from the war party (at first in loot and then in advance)... or irrational cuts of the haul or something. Eventually a few shuttles on both planets are downed and the locals make like those Africans in Lord of War and by the time the recovery team get ther its little more than a skeleton.
Cue enterprising nobles paying for this stuff and insert a nice boost to research and tech levels. Eventually someone makes radios... then radios good enough to taunt the other planet. Which eventually leads to both sides noting their respective ferrymen had undesirable price increase / spontaneous upswings in equipment failures at the same exact time. Cue both sides deciding its time to cut out the middle men. One war pair of wars later and you have your set up as both side attempt to figure out space flight on their own... the hold up may be the controls are so convoluted that 85% of them may only cause random lights to turn on and off and blink and flash... and the wiring is spaghetti logic.
Another reason for this landmass model is that your going to have one hell of a time running an iron age society on a global level if your constantly needing a navy and ocean crossing to communicate. With one major landmass you can set a nation up that way... remember your insisting that post war and a few hundred years after the fall they are maintaining military against each other and there are only two societies are actually worth uplifting on two planets. I find it entirely suspect that both world would count it as a good idea to reestablish mutual global governments at the same time anyway... unless the societies are just rigged to function that way. In which case they may have ended up nuking each other simply as a matter of deciding where the capital should be getting completely out of hand and the scientists not winning the race to build a capital city space station exactly between the two worlds. Something about actually researching how to make such a things and the implementation process taking longer that drunk (on power or booze), screaming politicians can order buttons to be pressed.
Just the first thing that came to my mind... but the main thing to remember is that if something as odd as two planets in exact tide killing orbit with each other is the basis of things... that will effect everything eventually.