The two baggage cars behind the RPO aren't that unusual for a holiday weekend. The three cars ahead of the RPO are definitely unusual.
If you go through the entire sequence that's online, and if you assume that the photo dated October 1 is mis-dated (and should be September 1), then it looks like no. 477 hauled the three baggage cars in train no. 115 on September 1. No. 470 powered no. 116 from Durango to Chama on September 3, where no. 482 took over.
That would leave Sept. 2 for loading or unloading.
What's in the cars? If I had to guess it would be company material. Maybe a new agent or operator's furniture, or something for the shop?
JAC