This is my denarius with a Roma head on the obverse and a biga on the reverse. Common theme, like the ones with a quadriga.

Obverse identifies the value (X which meant 10 asses) and ROMA
Reverse identifies the moneyer, L FLAMINI CILO. Reference RRC (Crawford) 302/1. I see this attributed to the years 109-108 BC but it is unusual to see a type still marked 10 asses at this late date.
It is still on good shape, with 3.83 g. The one curious thing with this one is that someone took the work of marking another X on the obverse, in the field in front of Roma. It was in antiquity because it is oxidized over. What was wrong with placing the X below the chin, it offended the layout preferences of some user of these coins?

Or perhaps it had something to do with a devaluation of the copper coinage? There are some denarii marked XVI. Was someone intending to reaffirm this is worth 10, not 16, during the time of devaluation?
There is no answer. It is just what it is, something odd.