A distinction between copies, versions, and variants is at work here.

The enzyme is a trimer with three active sites shared between adjacent copies of the protein.

Vivi is an art student, and much of the novel discuss relations between copies and originals.

The difference between promotional copies and the official release is a small black line through the bar code.

The track lengths may also vary between copies since the original tapes were digitized.

So far this technique shows the most promise, because you don't need to adapt an application to talk between multiple copies of itself on the network.

To make a careful comparison between copies of text, manuscripts, books, etc; put together information from different sources.

This is often a source of errors as it has troubles distinguishing between unique contacts and copies.

Turnover is a consequence of frequent molecular exchanges between copies of a family.

In this scenario, gene conversion is of potential benefit in maintaining homogeneity between copies.