12 volt splice

I have a head unit which requires 2 sources for 12 volt constant power (in addition to accessory power). Both of these wires, requiring a 12 volt constant source , are already fused. The car head unit harness already has one wire for constant power. Is it an acceptable practice to use the same car harness wire, splice a second wire off of it and use it for the second wire requiring 12 volt constant? Or would it better to use an entirely separate wire.

 Most likely this is a panasonic headunit and yeah as long as both are fused seperatly you are ok to put  those together.

Thank You.