@Kwad3d Please post your current config.g, send M115 to the Duet and post the response (shows firmware version) and, ideally, post a screen shot of the bed mesh.
Inconsistent probing can be caused by many things; probing too fast, poor wiring connections, electrical interference, mechanical issues (slipping or binding moving parts) and so on. It can, of course, be caused by electronics malfunctions or firmware bugs, but these are pretty rare! Most likely a configuration error is to blame, which is why seeing your current config.g would be most useful.
Ian