first.. don't run your sip sets through the SRC, you can record with the MBG too (same product, different marketing names). Just add the MBG to your call recorders list of SRCs and point your sip sets at their proper icp. saves the extra hop and added delay in voice traffic too.
otherwise, for sip, the only resiliency method we have is using FQDNs with multiple A records. You'd have to populate DNS with your two SRC ip addresses and use that when configuring the "icp" (src) address in the TW MBG.