A coin that has been overstruck, i.e. coined more than once.
The printing of one character over another, as - on top of L to produce Ł.
Overtype (feature where input replaces existing characters instead of being inserted before them)
To overreach oneself while striking.
To cover up (a design, mark etc.) by stamping another on top of it; to superimpose a mark or logo on (a coin, stamp, etc.).
To strike (something) too hard.