A set over set in poker is when two players make a set, also known as a three-of-a-kind hand. While both players have a strong hand overall, one is in the unlucky position of being faced with a stronger set.
Set Over Set Poker Example:
Let’s say you have a Qc Qd hand and your opponent has a Td Ts hand. The board after the river reads Qs Jc Th 4s 3d. Both of you have a three-of-a-kind, but yours is of higher value, so you’ve won in a set over set scenario.