I certainly did notice that error. The roof vents looked identical, but the front ends and doors are clearly different styles. I fondly remember the R12's - after years on the Flushing line they were intermingled with newer IRT equipment on all Broadway/7th and Lexington services. It was rare to find them in a solid train - except on the 3rd Ave. in its final Bronx years - and then only four cars long.
I remember seeing the Steinways on the 42d St. shuttle in the late 50's and early 60's - do you where else they migrated in their careers besides 42d St. and on the 3d Ave. (Bronx) elevated?
Best wishes for a Merry Christmas and a Happy New Year.