When you place in the 1st, 2nd, or 3rd on the podium of a competition, the ETH you receive already includes the threshold rewards, if any.
For example: You place 2nd in Super Rare Cap 240 and the ETH reward for 2nd place is 0.21 ETH. Your lineup scores over 250 points and the score-based reward for scoring over 250 is 0.03 ETH. Since you placed 2nd place, you win 0.21 ETH only.