Systems for and methods of determining likelihood of reference point identity duplication in a positioning system are disclosed. A method of determining a measure of likelihood that a designated identifier is shared by wireless devices includes determining reference points associated with any wireless device having a designated identifier. The reference points are a geographic position at which signals from any of the wireless devices were detected and/or wireless devices from which signals were also detected within a selected period of time during which the signals from any of the wireless devices having the designated identifier were detected. The method also includes determining statistical information about a temporal distribution of detection of signals of reference points, a spatial distribution of the reference points, and/or a cardinality of the reference points and determining a measure of likelihood that the designated identifier is shared by wireless devices is based on the statistical information.