There is a bit of a history of Prokopowichs marrying Beykos. My grandfather's aunt (Catherine? Prokopowich)married a Beyko. Some of their children came to the Dauphin area. Either Catherine's sister in law or daughter (I don't recall which, and I don't have access to those documents at this time) married back into the Prokopowich family, but a more distantly related one. These are majority of the Prokopowichs around Dauphin. My grandfather was the sole Prokopowich in his immediate line to come to Canada also initially to the Ashville/Drifting River area west of Dauphin.
As for the spelling of Prokopowich - it seems that that was really up to who was filling out forms. I've seen all the versions - first names were equally miswritten. For my grandfather I have seen Nick, Nicholas, Nikolay, Nikolai, Nykolo, Mex (don't know how they got that one!) etc etc etc.