There are counterstamp collectors, It could be a love token with the reg being short for Regina, Carried by either a sailor/solder while away from home or the lady waiting for their return. some are more elaborately done. others crudely . There are others that have social or political meanings as with the Irish troubles counterstamps. you can google the word or search on this site as there are a good number of threads on them.
TEC 4981 http://tecnews.org/