Personally, I think that there should be a way in Cabrillo to declare a contact as null, if you are not sure about the call or exchange. (Pardon me if this has been incorporated, I suggested it years
This ability does exist for CQ WW and CQ WPX Contests. Simply place X- in front of the QSO line and the QSO will not count for your score, but will count for the other station. Example: QSO: 21150 PH
Yes, Goran this was incorporated a few years ago. The "QSO:" tag at the beginning of the line is changed to "X-QSO:" to exclude the QSO from checking. This is documented clearly in the Cabrillo V3 sp