I'm pretty sure the stones used at the end of Infinity War and Endgame are (supposed to be) the same Sacred Timeline stones. The Avengers just move back and forth in the Sacred Timeline, they (supposedly) don't go to different timelines. Or that's the idea behind taking the stones back in time at the end of Endgame.
Let's be clear though, this isn't hard sci-fi, there's always quite a bit of handwavium used on the MCU plots
