Double - on 3 similar PC power supplies. I was concerned, as it was reading my PC with one drive and no monitor at
100W, which seemed unlikely. A few minutes later with a few resistors and a scope, produced waveforms for current, which looked rather odd, and seem to be the reason it misreads. These things will only sample the current so often, and it seems not quite often enough for some loads, so they make mistakes.(For all other devices including various sizes of SMPS it worked fine)