[bholdr]

I aggree with andyb: the bring-in likely isn't calling raises on third with just a small split pair. I'd likely think (depending on the player) he was drawing on a three-flush (and/or straight potential) on third- in a multiway pot his play would be justifiable... he also may have a decent buried pair, no? the double bet seems like a standard knee-jerk reaction, esp with the potential case card out. lots of players will always double bet when they pair their door card. i'd call at least.

so: I would think that i was either way ahead, or a little behind- he could have just made two pair as well...

this may be a good time to consider a raise to isolate this player, depending on your relitive position and the other players in the pot. if he DOES have two pair, you have a reasonable chance to out-draw him, and the pot is giving you good odds to try. if he has only one pair, you're way ahead. if he did hit trips, he'll probably re-raise and let you know, you can check/call from there.

one thing: in order to give quality advice, it would help to know (at least) the stakes and site you're playing and your position relitive to this player. reads on the others and the dynamics of the game (how many players? tight/loose game? any mainiacs, donks, rocks or solid players in the hand? etc...) the more info the better.