New Post: Set Default Calndar

In MFCMAPI, where do these two calendar folders live? Do they have the same name? Do they have the same parent? Or is one the parent of the other? After migration, if you create a new meeting, which calendar does it end up in?

I would propose you test moving items into that calendar using MFCMAPI and see if they still function OK. Make sure you move and not copy. Once the other calendar is empty, you can try deleting it.