That's what it looks like to me too. Several older unicorn mold chips appear to be compression-molded, with square edges and no injection mark. Examples include NCVs from Ed's Tahoe Nugget, Plantation in Sparks, and these from the Reno Horseshoe. Newer chips have rounded edges and the injection mark in the groove on ove side, like the blue 50¢ chip from Reno's Circus Circus. My guess is Chipco developed the unicorn mold to make "cheap" chips, and later redesigned the process to make the chips even cheaper to produce.