Continuity test with your multi-meter to the solder pad for the function and function common, if you can.
Two LEDs touching each other may not create a short on the function output; it depends if the LED contacts actually touch each other, as well as which wires your resistors are attached to. Possible outcomes might be frying the LEDs but not the decoder, frying the function output without frying the rest of the decoder, the LEDs not working but no permanent damage, or everything being fine. I think it's unlikely you'd fry the whole decoder although I can't guarantee it.