Karen,
Yep - you have hit the first show stopper with multiple tunnels using the same IP scheme!
I have 115 tunnels from my D/C's going to remote sites - no issues, as I have allocated specific IP address ranges.
My tunnels have specific /30 addresses out of a /24 range. I use loopback's for source & destination's for the tunnels - the loopbacks are part of their own /24 with 255.255.255.255 subnet masks.
To be honest if you have planned your IP subnet structure correctly - you should have no issues giving your 60+ tunnels unique ip addresses.
HTH.