During a remodel I moved light/fan switchs from one side of the door to the other. I had a double gang box with 2 single pole switchs and now have single gang with single pole double switch. I have a tried the old wiring configuration with the new single gang double switch and it blowes the breaker every time I turn one switch off. What did I do wrong?

Are you sure you wired them the same?

Are you sure it trips when you turn one switch off but not when you have both switches on? Hard to say what the problem is with out knowing how you wired the switch