The difference between manual and automatic duplicate merging is that an automatic procedure, if written correctly, can preserve the comments and history of all instances of the sentence. It can also preserve audio, if it exists, for one of the sentences. (If and when we allow multiple audio files for a single sentence in the future, it will preserve all the audio.)

The problem is that we don't have a good automatic duplicate merging mechanism right now. The script that was used in the past was run infrequently (perhaps only several times a year). In part, this was because it was a very slow procedure with many restrictions on when it could be run. It also lost audio links. We're in the process of writing new code. I consider this our second highest near-term priority, after restoring access to the wiki and our help/FAQ pages.

In the meantime, there are two "camps": those who believe that contributors should look for existing sentences before adding possible duplicates, and those who believe that this is too burdensome and thus should be a task left to the software, whenever it is ready. I'm not going to comment on the arguments made on both sides, other than to say they both have some validity in my eyes.

However, there is much that can be done to maintain peace in the time before the duplicate merging code is written. It's a good idea for everyone to look for possible duplicates (especially when contributing sentences consisting of common words). On the other hand, I don't see much use in corpus maintainers deleting duplicate sentences. When we have such a high number of duplicate sentences (~25,000 for English is the figure I've seen), any manual deletion will have no real impact. Nor does it seem to prevent people from contributing duplicate sentences. It does, however, succeed in annoying people and leading to arguments, both of which are counterproductive.

Thus I urge everyone to be patient until the duplicate merging code is complete and in use, and to refrain from either contributing duplicate sentences or from deleting the ones that exist.

>Why do you care, if another user delete it or automatical script delete it? What's the difference for you?

The difference is that if native speakers only search for exact duplicates just to delete them, they won't have the time to find mistakes in sentences and post corrections in comments, which, in my opinion, is a more urgent thing to do, rather than removing manually duplicates

but then, we could even miss new translations by doing that. plus, users might actually learn something with those sentences, so it's far from being a waste of time if they translate them, even if they produce duplicates