The Riverside library photocopying machine was likely purchased to accommodate the college paper they stocked.
A photocopying machine, where students could secure 8 1/2 X 11 inch black and white copy of printed or typed material, was available at the library for ten cents in 1966. Hours of service are: Monday through Thursday 7:45 a.m. - 10:00 p.m.; Friday 7:45 a.m. - 4:30 p.m.; Sunday 1:00 - 5:00; 6:00 - 9:00 p.m.
This is nothing conclusive, but nevertheless is food for thought. The Bates letters were written on lined 8 1/2 X 11 inch paper, and the carbon copy Confession letter paper was torn top and bottom. This may very well have been torn to remove distinguishing features from the photocopying process, that may very well have identified a particular machine and specific location.