Re: Did anyone else realise this?
when was it tht they existed at the same time, I never once saw a game where they both existed at once
Lol c'mon man, the similarities you perceive between both worlds are so tenuous as to be surely nonexistent. If they really are the same world, the developers would've made it more clear and you surely wouldn't have been the first one to realize it.
Someone already mentioned the cutscene of the conversation between Xigbar and Zexion in the Castle That Never Was (great scene btw) where Xigbar mentions that he just recruited Marluxia.
358/2 Days starts right after Roxas's "birth" which is exactly when Sora became a heartless in KH1. Shortly after Roxas is born, he is taken to the World That Never Was. Traverse Town still existed at this time.
If you still don't believe that, remember the cutscene of Xigbar and Zexion. Xigbar mentions Marluxia, and because Marluxia came before Roxas, then The World That Never Was existed before Roxas was born, meaning that Traverse Town, having existed before Roxas as evidenced by you playing KH1, existed before Roxas was born as well.
If you still persist, Marluxia was recruited the day before Xigbar had that talk with Zexion. This means Roxas (and Larxene) haven't been recruited yet. Directly after KH1, Marluxia confronts Sora, setting the scene for Chain of Memories. If you what you say is correct, that would mean Marluxia was recruited during the very short time KH1 ended (and all the worlds were restored, meaning no more Traverse Town and in your "theory" the creation of The World That Never Was) and when Chain of Memories began. But this makes no sense, because Roxas was recruited before KH1 ended and after Marluxia.
If you still want to hold on to this "theory" I have a dozen more "disproofs" I can bring up like the spacing of time in 358/2 Days which is nice enough to include a timespan, ranging about 358 days lol