In terms of movies, Star Wars being the most recent example. There are 2 releases listed, 1 of the is an Internal but since that is not meant for courier distribution why is it not listed Dupe?
well, here's my take on it
there are several reasons i can think of offhand why a release might be tagged as internal. usually (but not always) it means that the release would normally be nuked for one reason or another. i think it is the exception rather than the rule when a group actively opposes their release spreading beyond their own members; more often, it is just something done when the situation calls for it, to identify that the release is not to be considered (formally, at least) as "entered into competition", as it were.
i think one of the most common reasons why an internal might be produced is by request of a siteop or other toward whom the group is inclined to be accomodating. for example, it might be that there is already a dvdrip of some movie available, which has some minor problems, or is not quite the quality that it could be (but is quite good enough to propogate without being nuked). generally, a "proper" of this movie, which corrected only minor problems or inconsistancies, or which is technically in better conformation to scene "rules" because of some insignificant technicality, would be seen as petty, or as an attempt to 'get away' with a dupe without legitimate justification (cough*
http://www.isonews.com/release.php3?releaseid=51695 * cough).
however, perhaps this is the favorite movie of a siteop on a site affiliated to the release group, and he'd really like an expecially high-quality or perfect version... so, the group does a high-quality version, and their friend is happy. but, now that they've done the work, and produced such a nice-looking rip, it seems a shame for only one person to get it... and besides, there are plenty who are happy to toss out the race winner's version, if the dupe is of better quality... so they release it flagged 'internal'. this is equivalent to saying "hey, we're not offering this release as a challenge to the current one, as a 'proper', nor are we trying to count this as a regular release based on some minor differences...we just did this for ourselves, if you want it cool, if not stfu, it's an internal & only meant for us anyway really." this way, if a site doesn't like the idea of multiple groups being able to release the same thing, they can choose not to allow internals on their site. internals propogate much more slowly, and less completely, but still those who want it can probably get it.
another reason might be just the opposite of the above... for example, a group is the first to release a screener, but it turns out to have been encoded at a non-compliant bitrate... they know that it's got reason to be nuked, but they don't want to redo it, and they know that there are plenty who would like to see it anyway, so they go ahead and release it, but call it 'internal'. those who don't care if it's non-compliant can get it, those who do are forwarned, they can always look at the nfo to see why it's internal.
then there are small groups (or fxp boards or whatever) who would like to 'release' stuff, but just don't have the means to compete with the established groups, who can always beat them to a release... so they do an "internal" with some minor differences and hope it gets spread around enough so that ppl start to notice them, and think that then maybe they'll be able to get a foothold on some sites that accept internals. this especially happens with dvdrips, since it takes no special "contacts" to get a post-retail-release dvd & rip it. sometimes this sort of 'internal' release is in fact of better quality, since the releasing group can take more time on the encode (having already lost the race to release the vid, time is no longer much of a factor).
occasionally, there is a release that really is meant (for one or another reason) to NOT be spread beyond the group itself, or their close affiliates/friends. in this case, i personally feel that the desire of the group should be respected, and that their release not be exploited for its 'credit generating' potential or whatnot.
or maybe sometimes it's easier to just re-rip an older movie than to try to find the original release of the thing.
star wars was sort of a special case, it seems to me... all of the multiple TS releases were pretty much tolerated, because everyone was well aware of what massive demand there was for a good release. by the time that 'internal' you mentioned came out tho, there had already been 4 or so attempts (none of them being much to speak of), and so i think the group realized that ppl were getting sick of it, and that unless their release were significantly superior, it shouldn't really be released as a proper ts. well, their TS was arguably the best to date (at that time), but still wasn't all that great, and they knew it, and so rather than be "entrant #5" or whatever, they chose to flag it 'internal'. probably a good thing, since CTP's version was released soon afterwards, and it was clearly the best TS of the bunch. (actually, if i remember correctly, there was another 'internal' after that even, a re-encode of ctp's, or some lame thing).
gah, what a bunch of time (mine & yours) i've just wasted blabbing on about bullshit. jesus.