I think I understand your question...
K32HI, for example, is a fill-in or translator station for KOLN. The displayed call sign will be KOLN, with occasional station identification of their translator stations as required by FCC rules.
KHGP has no translators or fill-in transmitters. They will identify as KHGP.
You can find a wealth of information for most of the call signs at
http://www.rabbitears.info/market.php
Two antennas can be on the same mast. Try to maintain at least four feet separation. In most cases, the UHF antenna will be at the top, the H-VHF four or more feet below. It's OK to try variations on this to 'tune' your system for best performance.
Here is a bit more on rotators vs. alternatives:
http://forum.tvfool.com/showthread.php?t=2882