Can a CCU be used in the same DCN-NG system as a CCU2 or CCUB2?
No, this is not possible. Mixing CCUs and CCU2/CCUB2s in a DCN-NG system is not supported.
It’s also not possible to use a CCU as a spare unit in case of failure of a CCU2/CCUB2 in a DCN-NG system.