I would say 99.5% likely to be a vise job. The topmost tips of UNITED, if mirrored, seem to fit into the grooves. The inside edge of the second coin's rim is probably what pushed that little fin out above the indented letters. On the obverse, the flattened area is where the jaw of the vice or press pushed against the rim and crushed it flat. It must have been a smooth, flat object (possibly a third quarter) or the vice would have left patterned marks.
If it isn't a vise job, it will certainly be enlightening to learn what other process produced that pattern.