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human
[MCU] Endgame implications

Time travel makes whole new timelines, in some of which thanos is still around in a presumably gets the stones and does the snap.

This is where things can get confusing...

If the avengers in those timelines go back in time to get the stones will they find our avengers already there taking them? (as that what happened in their past?) 
Would this keep happening, spawning more and more timelines with more and more avengers all trying to get the stones?
gpt
The way the film presents it, when you go back in-time you create a different timeline from your own. So any Avengers in alternate timelines going back in time, will just spawn a new timeline *based* on their own.

So going by the movies rules, taking Captain America as an example. If CA#2 from alternate timeline went back in time to get time stone, to that exact point he fought CA#1 he would spawn a new timeline. This new timeline would now have CA#1, CA#2 and CA#2 from the future.

If CA#2 from that timeline went back in time to that moment, there would now be 4 (including himself). And so on and so forth. So there really could be an alternate universe now where there are dozens of Captain Americas, at that point in time, fighting for the same (but not same) time stone.