I have a ASR9K with 1 RP and now I want to install a second RP. This new RP has the same IOS-XR installed (4.0.1) that RP already installed, but it has a different number of SMU´s installed and when I install the new RP this have the "IOS XR PREP" state.
Can this behavior be due to the new RP has a diferent SMUs installed?
When the active RSP sees a standby, it verifies that the standby has the same packages as the active. If that is not the case, the active RSP will automatically synchronize the packages (adding or removing PIEs and SMUs). During this time the standby RSP will be in XR PREP state.
So the behavior you see is normal but the standby RSP should move into IOS XR RUN when the sync process is over.