Dedupe This! allows you to remove duplicate entities from a folder. For example if you have an Actor folder called Monsters and over time you've ended up with 30 copies of the same Goblin actor, Dedupe This! will leave a single actor in the folder and move the rest into a new folder called Duplicates where you can edit or delete them.
Please check out the Wiki for more info/how-to.
If you have an issue or want to suggest an enhancement, please use the Issues