First one was one of Andy Cairns old cams: solid shafted #2 or 2.5 Friend placed at an angle in a pod on Eagles Domain. Fell (20 footer) out of wet crack onto friend, which rotated out of crack & turned 20 foot fall into 50-plus foot fall. Afterwards examination showed one side of cam had broken trigger wires & possibly internal springs at point where wires connect to cams; on that side of the unit the cams were then free to move allowing cam to rotate around them when placed. Not sure after the fact if this was the bottom or top side in the placement, suspect it was the bottom.
second time was when climbing Ultimate Everything before the FA when it was still a project. Had a yellow older TCU, again at an angle, in a pod excavated from dirt in a muddy crack. fell off, weighted TCU. seemed to hold and lowered on it but when i was about three or four feet off the ground it ripped. examination showed TCU, that was of the type with inserted (aluminum dowel) cam stops rather than machined cam stops, had the cam stops on one side completely deformed and bent out of line, allowing cams to completely rotate around axle.
sent that one back to Metolius and they gave $15 discount on new cam as they claimed it was too old to warranty.