Duplication is the act of making an exact copy of something, or the copy itself. When you hit copy and paste on a computer, you're creating a duplication of whatever you selected. A teacher might duplicate a worksheet so every student has one, running the original through a copy machine to produce identical versions.

Duplication can be incredibly useful. Scientists duplicate experiments to verify their results. Musicians duplicate recordings so people everywhere can hear their songs. Before the printing press, monks spent years duplicating books by hand, copying every single word.

But duplication can also be wasteful. If three people on a team accidentally duplicate each other's work, they've wasted time and effort. In government or business, duplication of services means two departments doing the same job when one could handle it.

The word carries a neutral tone: whether duplication is good or bad depends on the situation. Duplicating your favorite family recipe to share with your cousin can preserve something valuable.