These two locos are inspired by real world counterparts:
The engine on the left was heavily inspired by model 8 of set 10183, Hobby Train and a similar looking GP9 model numbered 13 from the real-world Wabash Frisco and Pacific 12 inch gauge railway in Glenoce, Missouri.
The engine on the right (The H10-44) was heavily inspired by engine numbered 704 from same railroad in the real world. That real H10-44 engine is painted differently (plain black) but I though it would make more sense to have it wear the same paint scheme as the other WFP engine, GP9 number 13. The LEGO version was modeled after the H10-44 seen in the defunct Railbricks Magazine number (issue 1)
Wabash Frisco & Pacific number 704 is a H10-44 model, built by Fairbanks Morse in late 1949 as part of a an order of ten locomotives. It was built to switch cars in the WF&P yard at Glencoe, but has wandered onto the mainline from time to time. The engine managed to avoid the renumbering scheme of the 1980's and still works the yard and nearby industrial tracks of Glenoce today.
Wabash Frisco & Pacific number 13 was built by Electro Motive Division (EMD) in early 1962 as a GP-9 diesel locomotive and as engine number three out of a twenty five engine order. It was built as multipurpose unit, and could handle freight or passenger service, and as such was painted in the generic red paint scheme with a white stripe from end to end located just under the cab windows. The engine served almost thirty years under the Wabash Frisco & Pacific (or WF&P, as it is known) before being re-engined in the WF&P company shops at Glencoe, Missouri in the late 1980's. At that time then engine was renumbered to it's current number of 13 from it's original 813 due to mass engine retiring moment and a renumbering scheme.