Yep. Try the MFJ-1272 family of switches. These are listed as "TNC-Mike" switches, but they are in fact 8 or 9-pole A/B switches. Their intended use is to switch an FM rig back and forth between a microphone and a TNC. Obviously, the "TNC" can simply be another microphone, if you wish. They come prewired in a variety of ways for a variety of rigs, check out all the part numbers.
http://www.mfjenterprises.com73, WB2WIK/6