Hello,
I hope that you are doing a great day.
I have researched about your concern and according to the documentation configure multiple instances of BGP is not supported on the ISR generation 2 IOS. On the following link that corresponds to the Cisco IOS version 12.4T, states the following:
"A router that runs Cisco IOS software can be configured to run only one BGP routing process and to be a member of only one BGP autonomous system."
http://www.cisco.com/en/US/partner/docs/ios/12_4t/ip_route/configuration/guide/tbrbover.html#wp1043334
I hope this will help you.
Best Regards.
Cristina Alvarado
Cisco Virtual Engineering - Partner Help.