anyone ever get their car dynoed at 2 different dynos with the same tune but each dyno say something different.

i made 215whp on 2 different dynos with the same tune, then went to get the car tuned again and the 1st run on the 3rd dyno i only made 187whp at that point nothing was changed yet. so how can 2 dynos be that far off from each other. at the 3rd dyno the guys say is off a little due to calibration issues with the rollers (he says it reads lower numbers) and the 1 and 2nd dyno were mustang dynos i think (not sure i just saw mustangs on them before i got there)

either way i got out of the last dyno with 232/174 on a hot motor with a dyno that reads low numbers. so i think i might be right at my goal of supercharged 250whp on a basically stock gsr motor

but anyone dyno experience please tell me what you think