Thanks Yutaka, that did the trick!
A new command would be useful, particularly for people who don’t scripting or RegEx, as a lot of other Text Editors include a simple menu option for removing duplicates. It would also allow you to highly optimise it, and also include an option to keep the original order (ie. so you don’t have to sort it first), which would be useful.
One of my other suggestions was for a simple RegEx library feature, so you can create or import Regex’s with a name, optional description, and possibly find settings. This would allow you to select the relevant regex from the library list and then run it.