This article is from the misc.writing Writing FAQ, by Wendy Chatley Green firstname.lastname@example.org with numerous contributions by others.
If you submit a photocopy, make sure it's clean and
clear; it also doesn't hurt to explicitly mark it "Not a
Simultaneous Submission" (if this is the truth), as some
editors assume photocopies are simultaneous. NEVER submit
your only copy of a manuscript; tragedies do happen.
Photocopy the manuscript, back up the disk--not vice versa.