What we discovered since we started shooting in 3D is that we have seen rangefinders read a white or tan animal target 2 to 3 yards different than a black target.Rangefinders are affected by weather conditions and reflectivity. They are not fool proof. Owners manual should explain.
This is why we bought a Bushnell Broadhead to try out. So far it doesn’t matter what we point it at it has been within .3 of a yard in real measured distance.
In reality most guys can’t shoot good enough to know. But when you can nail 12 rings a high percentage of the time you know when the distance wasn’t right.