I don't know what either radio normally draws, but seriously doubt if it will be 20 some amps just in the receive mode. So, you can probably have both on, and connected to the same supply. Only transmitting with one at a time will probably work too (not knowing the radios, that's just a guess).
- 'Doc
[Listening to yourself transmitting with the other one isn't exactly a real good idea, possible, just not very good for the listening radio. But you knew that anyway.]