Dyno question

[crice]

If you're using a 'snapshot' type feature on the dyno to correlate engine speed with roller speed (i.e. hold the engine at say 4000rpm in your chosen gear and press a button to tell the dyno software you're at 4000rpm) rather than use and inductive clamp, injector signal, OBD or whatever to feed an rmp to the dyno; what would be the effect on the power/torque plot if you (inadvertently or otherwise) mismatched the actual rpm with the rpm you've told the dyno you're at when doing the 'snapshot'??
Reason I ask is I think this is what's happened with a dyno plot I'm looking at with an unrealistically high torque curve. The power cure seems sensible (albeit 'shifted' a bit lower in the rpm than I would expect) but the bit I can't work out if proves whether the plot is right or wrong, the power and torque do cross at 5252rpm on the graph.
Anyone? Thanks.