Answer: overprints

AnswerCrossword Clue
OVERPRINTSStamp collectors' delights
overprintsPrint too many copies or too much of
overprintsPrint additional matter on (a stamp or other surface already bearing print)
overprintsOVERPRINT, to print over something already printed
overprintsPrint (additional matter) on something already printed
overprintsMake (a print or other positive) darker than intended