cross-post

cross-post [Usenet] vi.  To post a single article
   simultaneously to several newsgroups.  Distinguished from posting
   the article repeatedly, once to each newsgroup, which causes people
   to see it multiple times (which is very bad form).  Gratuitous
   cross-posting without a Followup-To line directing responses to a
   single followup group is frowned upon, as it tends to cause
   {followup} articles to go to inappropriate newsgroups when
   people respond to only one part of the original posting.