carbon copy

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A duplicate, as of a letter, made by using carbon paper.
2. n. A person or thing that closely resembles another.

Wiktionary

1. n. A copy produced in an alternated stack of ordinary sheets of paper and carbon papers. The pression applied on the top sheet (by a pen or typewriter) causes every carbon paper to release its carbon cover, thus reproducing the writing on the subjacent layers of paper.
2. n. Any duplicate.
3. v. To create a carbon copy of.
4. v. Internet make a copy for, send a duplicate to, cc

GNU Webster's 1913

1. n. originally, a copy of a document made by use of a carbon paper, but now used generally to refer to any copy of a document made by a mechanical process, such as xerographic copying.

WordNet 3.0

1. n. a copy made with carbon paper