user2811: I use a single radiomic (Sennheiser AVX) but now need a second one. Will the second conflict with the first one in terms of frequencies? Or would they automatically find different frequencies to operate on?
Update: now operating two Senn AVX sets, and they work together perfectly.

user13978: In most cases you can choose a frequency for the sender / transmitter to operate on. Interfering with another wireless mic is only one problem which might make switching frequencies necessary. You can also encounter other radio interference, not caused by other radio mics. Apparently the Sennheiser avx does this automatically for you, but I would assume there is also a manual way to select frequencies if that process fails.

user12218: These wireless microphones specifically designed not to interfere with each other. They will automatically find their counterparts but can only send a signal to one receiver.
You should be OK. 

user14256: Recent digital wireless products are more likely than not to have automated features which both search out available channels, AND to automatically pair transmitters and receivers.  However, legacy analog kits are much more vulnerable to problems of interaction and interference with other similar wireless kits being operated in proximity.

2811: <p>I use a single radiomic (Sennheiser AVX) but now need a second one. Will the second conflict with the first one in terms of frequencies? Or would they automatically find different frequencies to operate on?</p>

<p><em>Update:</em> now operating two Senn AVX sets, and they work together perfectly.</p>
 13978: <p>In most cases you can choose a frequency for the sender / transmitter to operate on. Interfering with another wireless mic is only one problem which might make switching frequencies necessary. You can also encounter other radio interference, not caused by other radio mics. Apparently the Sennheiser avx does this automatically for you, but I would assume there is also a manual way to select frequencies if that process fails.</p>
 12218: <p>These wireless microphones specifically designed not to interfere with each other. They will automatically find their counterparts but can only send a signal to one receiver.
You should be OK. </p>
 14256: <p>Recent digital wireless products are more likely than not to have automated features which both search out available channels, AND to automatically pair transmitters and receivers.  However, legacy analog kits are much more vulnerable to problems of interaction and interference with other similar wireless kits being operated in proximity.</p>
