I've got two Commander length 1911s but they're set up differently. The Nighthawk T3 is a CCO configuration and the other is an unaltered blue Colt 1991. Close enough that the Colt is put back as a redundant backup. At some point I'll add another Colt Commander so the two are more closely identical.
To me it makes perfect sense to have a matching backup that's identical in case the primary goes out of service (at the 'smith, damaged parts, etc). It'd be nice if I could afford another matching T3 but that's not gonna happen in this lifetime.