Say if I went through the end portal at one stronghold and my friend went through another portal at another stronghold, would we both be in the same end ?
Maybe.... though I think entering the end using two different portals is a dumb idea because you need 0-12 ender eyes each and there is a rare chance that the stronghold will be near spawn so good luck.
In java edition there is only one End dimension for each Minecraft world, regardless from which sfronghold you generated it. Famous youtuber Dream uses this tactic to fool and kill his firends in one of his recent manhunt series videos. Don't know about bedrock edition, i never played it.