1895, from carbon (report) + backup (letter.). A duplicate in some recoverable format made using carbon paper. The figurative feeling is from 1944. In addition as a verb, "send a carbon content (of one thing)," and therefore often abbreviated c.c.
a copy made out of carbon report
Dean explained how Annie Quincy too had ended her life, in a carbon copy fashion, with Edith mimicking the century-old life to its final extreme.