I bought an overstrike coin early this year. Spoiler alert, it may be in my top 10. The top coin is a quadrans with Hercules on the obverse and a ship's prow, right, on the reverse. The seller called the coin Cr 106/7a - Staff and Club series from Eturia. The a means the reverse has a staff, and there is no club on the obverse. I am not sure what qualifies as a staff on the reverse. If the line is not a staff, the attribution would be: Cr 56/5, Anonymous series from Rome. Crawford notes both Cr 56/5 and Cr 106/7 are known to have been struck over Cr 38/6. What do you think? The undertype is a Roma left / prow right semilibral uncia, Cr 38/6 from Rome. The back of Roma's helmet and neck and the mark of value are visible below Hercules head. On the reverse a curved back of a ship;s prow and two soldiers is visable. There are many variations of style of uncia. The best fit for what I see was from the Vecchi sale in Sept 1996, lot 30. I bought a similar overstrike a few years ago. That seller did not give Crawford numbers for the top of bottom coin dies.
Overtype is RRC 56/5 probably McCabe group G1. Style isn't right for RRC 106 staff. Great overstrike. Heavy for a quadrans.
[Better wait for the Roman Republican experts to chime in, but to me it looks like the variant with the horizontal staff (the line you mentioned).] (edit: I didn't see that @Andrew McCabe already posted above. His answer solved this question, I guess.) I have a semis with a horizontal staff: Roman Republic, anonymous issue ("staff and club series"), AE semis, 208 BC, mint in Etruria (?). Obv: laureate head of Saturn r.; behind, S. Rev: prow r., above, S and horizontal staff; in exergue, ROMA. 28mm, 19.86g. Ref: RRC 106/5 var (position of staff). Ex André Cichos. Here is an obverse die match sold by Bertolami a while ago (but sadly not to me). The staff is more visible on this one. Also note the hollow on Saturn's cheek that both coins have. I wonder what has caused it. Maybe scooping?
Thanks for your reply. The pic of G1.Qd.1 is a dead ringer (but not a die match). G1.Qd.1, from A. McCabe "The Anonymous Struck Bronze Coinage of the Roman Republic".