Dupe check
The check the release scene runs before putting a release out: has someone already released exactly this?
In the organised piracy scene only the first release of a title counted. A dupe — a second release of something already out — earned no prestige, wasted bandwidth on topsites and was usually nuked, marked invalid with a stated reason. Avoiding that was the whole point of a dupe check.
In practice the check ran against dupe databases: a bot on a topsite or an IRC service you queried with a title, getting back whether it had already been pre'd, that is, pre-announced. The rules were fussy — a release in a different language, format or from a different source could count as its own and therefore not a dupe. The system was the scene's way of turning "who was first" into a measurable sport.