1. A testbench system comprising: a device under test; a verification environment including a plurality of agents communicatively coupled with the device under test, wherein the plurality of agents transmit packets to and receive packets from the device under test for testing the device under test; and a non-transitory computer readable memory storing a packet tracking module communicatively coupled with the plurality of agents, wherein the packet tracking module includes: an associative data structure that stores a plurality of packet identifiers and pairs one or more of the packet identifiers with unique values derived from the packets; a counter that indicates which one of the packet identifiers that was most recently paired with one of the unique values by updating a counter value each time one of the packet identifiers is paired with one of the unique values; and a set of routines for updating the associative data structure and verifying the identity of one or more of the packets in the verification environment based on the pairs of the packet identifiers and the unique values of the associative data structure.