Yes, with CCM 3.3(2) in which restriction of running SRST feature on a default gateway was removed, you can run multiple routers as SRST routers to support more phones than supported limit on each router. However, please be aware of the call transfer/forwarding limitation if you're not running SRST 2.0 up on both routers. And also note that dial-peers/dial-plans need to be carefully planned and configured for call transfer/forwarding to work properly
This URL speaks about Cisco Survivable Remote Site Telephony should helps you:
http://www.cisco.com/en/US/products/sw/voicesw/ps2169/products_qanda_item0900aecd8028d113.shtml