I have both the VS100 and UA25EX.  Sonar Platinum sees both devices as MIDI inputs/outputs, and I can select either for a particular MIDI instrument.  Sonar Platinum sees both as audio devices, but if I select the VS100 for audio ins and outs, the UA25EX is grayed out and unselectable.  I can unselect all VS100 audio ins and outs, then the UA25ex becomes selectable.  
 
Is it that Sonar Platinum can only use one of these as an audio device at a time?
 
Is it that Sonar Platinum can use two different audio devices, but these two in particular cant be used?  I can certainly work around this by plugging and unplugging instruments and mics only as I use them, but I would rather have all my stuff hooked up at one time and just push the appropriate buttons to record a particular instrument.  
 

Depends on the Driver mode setting in Preferences > Audio > Playback and Recording. The ASIO specification permits the host to use only one I/O driver at a time. Some hardware manufacturers provide an ASIO driver which works with more than one device at a time. I do not believe Roland has such a driver for these two devices though. The other driver modes do not have the driver restriction.

Thanks.  That helps explain what I am seeing.
 
 Is there anyway to see in advance that a certain product has drivers that allow 2 I/O drivers at one time?