Jason, years ago I became very good friends with a gentleman named Tony Matkovich. Tony worked on the D&RGW in the 20s as a clerk in the Crested Butte depot and later went on to a long career on the Western Pacific. Tony told me that prior to the 3rd rail being removed from Salida to Leadville, he remembered way billing C&S cars on the D&RG at Crested Butte. Anthracite coal was billed to a smelter at Kokomo. He also said that C&S stock cars were sometimes on the Crested Butte branch and D&RG stock cars billed to points on the C&S. The stock rush season occurred at different times on parts of the two narrow gauge systems and the two railroads loaned cars to each other. Same thing happed with the D&RGW and RGS.
So having a D&RGW stock car at Como probably happened more than once.