Made double or duplicated; archaic past tense of the rare verb 'duplify'.
From 'duplify' (to make double) with the past tense suffix '-ed'. This is an extremely archaic term, mostly obsolete in modern English.
Language is full of dead words—'duplified' is one of them, replaced by simply 'duplicated.' It shows how English sometimes creates multiple ways to express the same idea, then keeps the winner!
Complete word intelligence in one call. Free tier — 50 lookups/day.