Changing A Double Dimmer Switch?

Recently my double dimmer switch half blew, meaning only one half of the lights in my living room worked, so i went to the same place and bought an identical double dimmer switch, only when i opened the package the backs were different, not to be deterred i took the old switch off and attempted to replace it with the new switch, but i can't get the new one to work at all. I have 2 red and 2 black wires and 1 yellow and green wire...i know where the yellow and green wire goes...but where do the red and black wires go? L1? L2? or C? and which goes where?