More likely to be Claudius, but probably impossible to tell. The countermarks are interesting though... maybe you could find them at the online Museum of Roman Countermarks.
TIAV is commonly read as "Tiberius Claudius Augustus". Strangely the "Claudius" would thus be missing from the countermark, and the countermark would show on almost uncirculated coins of Claudius. Another maybe more likely possibility would be to move the time of use to Titus (TIAV = Titus Augustus
The time of Claudius also makes sense, due to the large number of unofficial issues produced. The countermark would indicate official approval of the coin (whether it was an official mint product, or not).
+ On my coin tam where the emperor's head has 2 rectangular Countermarks on Coins of Caligula "IMP"..In my opinion this is a rare and interesting coin?
PS. I found an interesting page about the coins of Claudius https://www.flickr.com/groups/347820@N25/pool/page4/
The Romans usually were pretty good with standard praenomen abbreviations. Do you have other Titus coins using the TI rather than T? My favort C/M is a violation for TI reading TIBerius Caesar Augustus Filius. Or is there another reading for the B?
All these overprints were put on ordinary exchange rate coins of that time to confirm their validity for the territory of germany before and after the battle in the toytenburg forest known as the battles of Varus
