A beautiful example! An amazing coin. Which also adds the missing "Parthia v. Parthia", as the brothers, allies in murdering their father, Phraates III, fought for control. The younger Orodes II won with thanks to Surena, who would later defeat Crassus. This account by Bivar (1983), mentions the overstriking of tetradrachms in Seleucia and also discusses a question mark on who killed Phraates III. Also interesting is Sellwood's description of your Type 41.1 of Mithradates as "The designs have been reconstructed from the traces on coins overstruck by Orodes II".