Hi Friend,
Multi controller deployment, ( Master-Local) is a centralised config management model. Master controller is always used for Configuration, ARM and IDS where as Local controller is used for AP termination, processing user traffic and userrole assignment.
Here master always push the config through PAPI and always in sync hence it is required to have same image version in both the controllers ( Master and Local).
First of all it is not possible to bring up Master-local setup with different code, IPSec negotiation will be faild.
Hope you got some more clarity on this.
Please feel free for any further query on this.