That happened to me in a cash game a couple weeks ago for a nice $1000 pot... I had , one guy had , and the jackass w/ cleaned us up...
Not sure on the odds of TWO hitting (except that I would've had a heart attack and died )... But, one would be...
13 diamonds - 9 diamonds left in the deck... 9/46 * 8/45 * 7/44 = .5% of the time... Not sure if 2 flushes would be that times itself or what... As I'm particularly crappy at math stuff...