I have no hard evidence to prove that this coin is an ancient imitation - only pictures. But it seems to me unlikely to create in modern times such an ugly
fake. I believe that this coin is really worn (not made worn artificially by forger) and it is a
poor brother of the second coin I uploaded, which was sold on
CNG eAuction 354 (lot 588) in July 2015 for USD 170. And described as follows by someone who
had this coin in hand:
Galerius. As Caesar, AD 293-305. AR Argenteus (17.5mm, 2.73 g, 11h). Treveri (Trier) mint. Struck circa AD 295-297. Laureate head right / Tetrarchs sacrificing over tripod before city enclosure with six turrets; C. RIC VI 110b var. (obv. legend); Jelocnik 97 var. (same); RSC 216b var. (same). Near VF, toned, some porosity, a few marks on obverse. Very rare with this obverse legend.
Of course, it can't be excluded that the first coin is a modern
cast copy of a late barbarian imitation. But it would be a strange move.