Cisco PVDM modules

I have installed 1 PVDM2-8 Module to work with my VIC2-2FXO card and its working fine. The question is, do I need another PVDM2 module if I install a VIC2-FXS card or will it just use the first PVDM2-8 module?
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Comments
(or, just pull the FXO/FXS VICs to play around with conferencing, and put them back when you are done).
Check out the DSP calculator on Cisco.com (requires a CCO login).
CUCM SRND 9x/10, UCCX SRND 10x, QOS SRND, SIP Trunking Guide, anything contact center related