duplicate (adj.)

early 15c., "having two parts, double," from Latin duplicatus, past participle of duplicare "to double," from duo "two" (from PIE root *dwo- "two") + plicare "to fold" (from PIE root *plek- "to plait"). Meaning "exactly corresponding, that is an exact copy of" is from 1812.

late 15c., "to repeat, produce a second (like the first);" 1620s, "to double," from Latin duplicatus, past participle of duplicare "to double," from duo "two" (from PIE root *dwo- "two") + plicare "to fold" (from PIE root *plek- "to plait"). Related: Duplicated; duplicating.

1530s, "one of two or more things corresponding in every respect to each other," from duplicate (adj.). From 1701 as "another corresponding to a first or original, an exact counterpart or double of an original."