A single-head Universal machine cancel, it would be fed a stack of faced mail. The feeding mechanism can be adjusted to accurately feed individual mail pieces of a typical average thickness to the canceling head. My guess is this envelope contained a thicker enclosure such as a multi-page pricelist. Whatever the enclosure, the separator/feeder was not optimized for this non-typical thickness and fed some envelopes overlapped a bit instead of being sent through individually. It still achieved the goal of revenue protection.