I think John about sums it up. Though I do find the term reissue a bit miss leading.
If it's for a re-release of the film it should be called a re-release. A poster can be
reissued during the second release, so it's still a first release poster, but reissued,
if that makes sense... Happens quite a lot with Quads, and belgians. As John says
make sure the distributor is correct also, I'll post an example shorty.
One of the beauties of buying a Belgian poster with censor stickers, or Venues printed
on the top, is you know at least it is a genuine poster, just not from which release.