From what I could gather (novel readers, please correct me if I'm wrong), it's more like the MC time-travelled back into a different timeline instead of regressing to the past. In chapter 2, the artifact that he picked up stated something about his old world being officially declared as extinct, so he was being 'transported' to an undetermined date. We can take the word ('transported') quite literally since the MC remained in his adult body while his younger one exists. So the timeline that the MC is currently in isn't the one he was originally from but probably one of many, which explains why two versions of him exist.
OH WAIT. I MISUNDERSTOOD THE QUESTION. WTF.
MC basically lied to everyone, saying he was his own older brother, so now he had to roll with said lie since he's knee-deep in it. He used it as a front to explain how he knew about the ark dudes and stuff without knowing it was gonna come bite him in the ass.
So yeah no. He hadn't met his younger self before the day they rescued him from the orphanage. His younger self thinks MC is his older brother (the og one) and since MC was knee-deep in the lie, he had to act like he was. (DO I MAKE SENSE. HELP.)
Oh!!! So he really does have an older brother! (ﾉ*0*)ﾉ
Thank you so much for explaining, I was so scared that I missed a few chapters
♡(> ਊ <)♡
Didn't the MC traveled back to when the dungeon break was happening (where the allegedly dead student of his adopted father should have died)
But how did he met his younger self, created brother like relationship with him and then disappear and finally rescued him after atleast a year??
I think i missed something, SOMEONE PLEASE EXPLAIN TO ME!