If I snmpwalk a 7600 with dual sups with cpmCPUTotal5minRev I get:
CISCO-PROCESS-MIB::cpmCPUTotal5minRev.1 = Gauge32: 1 percent
CISCO-PROCESS-MIB::cpmCPUTotal5minRev.2 = Gauge32: 2 percent
CISCO-PROCESS-MIB::cpmCPUTotal5minRev.3 = Gauge32: 0 percent
I'm assuming I have another cpu on one of the boards. Are they numbered in the order they are in the chassis? If so, it seems odd the redundant sup would have high cpu.
Poll the cpmCPUTotalPhysicalIndex for these indexes, then poll entPhysicalName and entPhysicalDescr from the ENTITY-MIB to get the details for each CPU.
You can find what each CPU is by querying the Cisco-Entity-MIB, specifically the entPhysicalName and entPhysicalDescr OIDs. From what I've seen, modules such as the FlexWAN cards have multiple CPUs on them too.