1. A method for removing duplicate data entries from a database comprising a plurality of application server nodes in an application server cluster, said method comprising: tracking items using a plurality of ADA devices in a plurality of locations; receiving ADA observations over a network from the plurality of ADA devices; balancing a load of data communications including the ADA observations so that the observations are sent to different application server nodes of said application server cluster; filtering duplicate ADA observations at each application server node; and separately filtering duplicate ADA observations between the plurality of application server nodes.