A:Answer First, if I go right now and searched online would I get an answer? So my question is, did you search online?
So your question is too vague. One set of inputs? Is the input RCAs or High Level (wired)? If the signal coming from the back of the radio/receiver is RCAs then search online (I hate laziness)how to hook up 2 amps with online 1 set of RCA outputs. But since I'm already here, some amps have a signal output that allows for hooking up a second amp, if not buy 2 sets of RCA Y adapters; 1 for left and 1 for right. If it's High Level you may be able to find something online but if not, you'll have to connect 2 of everything lol.
Note: if you didn't know this you shouldn't be working on anything electrical or that involves common sense. But BOTH amps will have to be hooked up to power, ground and a remote. RCAs and/or High Level don't transmit "power" but signal.