When an article is posted simultaneously to multiple discussion groups only one copy of the article is stored in the spool The other copies, known as crossposts, are links to the main article
[Usenet] vi To post a single message simultaneously to several forums Distinguished from posting the message repeatedly (once to each forum) which causes people to see it multiple times and is considered to be bad form Gratuitous crossposting without a Followup-To line directing responses to a single followup forum is frowned upon, as it tends to cause followup messages to go to inappropriate forums when people respond to only one part of the original message
An article that appears in more than one newsgroup because the author selected more then one at the time it was posted Crossposting an article only takes up diskspace equal to one copy of the article