In one aspect where a load or a subset of one or more tags is in motion relative to an RFID reader system, the RFID system obtains tag readings and derives tag scalar or vector motional data e.g. tag velocity, tag acceleration, and/or rate of change of tag acceleration which can be compared to known tag motional information to distinguish true tags of interest from false positives which are unavoidably also within the field of the reader system. An antenna system may also make readings during distinctive movement patterns of true tags, such as vertical or arcuate movement and utilize computed tag motional data based on the tag readings to distinguish true tags from false positives. Two components of the RFID system may communicate information on identified tags, and/or interact (e.g. by silencing tags), so as to cooperate in identifying true positive tags.