These are four sheets of paper, written in blue ink. Page 2 is the reverse side of Page 1. The ink appears the same, but it is rare to find Minsky writing on the back side of pages in his handwritten notes for his PhD thesis.
Minsky, Hyman P. Ph.D., "Handwritten Notes for Minsky's PhD Thesis titled 1 Introduction" (1949). Hyman P. Minsky Archive. 503.