I would say that the caboose matches the railroad and the motive power may or may not match. If the motive power was leased from a controlling parent railroad or if one railroad took over another one. When C&O took over the Pere Marquette some locomotives were renamed C&O but running in PM territory they may be pulling a PM caboose.What I'm saying is the railroads would have to be related in some way to have unmatched power and caboose. Just my own thoughts I have no proof that this is true.
Ron