Cisco WAN :: 7613 - Redundancy With WS-SUP720-3BXL Module

We have Router CISCO7613,SSO redundancy configured with two Sup 720-3BXL running 12.2(33)SRC1 image. Even thought I've configured SSO, my standby sup remains in COLD state with the following logs generated.
 
Mar 20 22:07:32.514 IST: %ISSU-SP-3-PEER_IMAGE_INCOMPATIBLE: Peer image (c7600s72033_sp-ADVENTERPRISEK9-M), version (12.2(33)SRC1) on peer uid (8) is incompatible
Mar 20 22:07:32.514 IST: %ISSU-SP-3-PEER_IMAGE_INCOMPATIBLE: Peer image (c7600s72033_sp-ADVENTERPRISEK9-M), version (12.2(33)SRC1) on peer uid (8) is incompatible
Mar 20 22:08:48.263 IST: %PFREDUN-SP-4-INCOMPATIBLE: Defaulting to RPR mode (Runtime incompatible)
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These logs says that due to some reasons, the configuration is not being synchronized with active and standby sups and hence the redundancy mode remains in RPR mode and SSO not achieved, and hence COLD state. However, I couldn't find a reason why the configuration is not being synchronized, I've issued the command, redundancy config-sync ignore mismatched-commands, and everything worked fine, SSO achieved and standby sup came to HOT state.Now my query is, 

1. Why the configuration was not synchronized and standby SUP got in COLD state??
2. Since I issued the suggested command, at least, some of the mismatched lines in configuration will be ignored, Will that create a problem when my Active sup fails and standby become active?