Horseman advancing right, holding a spear / Inscription naming Ivan and giving his titles. 15mmx10mm, 0.67 grams. 

Seems to be overstruck on an older type?

The infamous Ivan "the Terrible" was the Grand Duke of Russia between 1533 and 1547. In 1547 he assumed the supreme title of "Tsar" ("Caesar") and ruled as such until his death in 1547.