This seems like an unlikely theory but I like the evidence that went along with it. Also if she did have a secret twin/doppelganger then the way Lebam most likely came into existence is by the copy machine that Dipper used.
No, I'm pretty sure rose knew all along that she would disappear, or more accurately, become steven. It's not that rose died or that she chose to save steven, she just became a part of steven when he was born
Hahahahaha - Slenderman From Creepypasta And Patrick From Spongebob
Someone came up with the believable theory that P.B (princess bubblegum) was alive for the mushroom war and was mutated from a human to gum due to the toxic waste from the nuclear bombs. Sorry if you came up with the theory! I taks ABSOLUTELY no credit towards this theory. Thank you for this GREAT theory