I'd raise it on the flop



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2-pair shouldn't be leading this strong (or at all) having flopped 2-pair/set - ESPECIALLY with the Ace and an EP limper in the hand.

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If the sb has got 2 pair, I think he should lead out and bet. An ace is most likely going to raise - and then sb moves in.

EDIT: Didn't look at sb's stack size. He should obviously try to check-raise