Well, different memories is simple, since we should all be missing about three years or so. At least all of our school memories and a bit more!

But, a different universe would explain two of you, at least.

[But he had his doubts, because there was a small something in the back of his mind, he would put it together soon at least. Well, depending on what people might tell him maybe he would put it together instantly!]

But, you're not completely wrong, we were in a game!