I don't know if this has been suggested before, but I would like to add some simple non-technical idea to minimize double entries in the future. This probably won't stop it completely, but I think a strong notification/reminder on top will be of great help for updaters. And what is needed to double-check.

The problem of double entry has been on my radar for quite a long time. It is normal for updaters to manually check whether the title has been added to the database or not, and there is no problem if the information is incomplete as other updaters can complete the rest. But if for example we only get a warning at the end of "This title has been added", there are still some that pass through the gap because there is a difference in typing whether it's uppercase or lowercase, or words that should be separated are instead connected and those that are connected are separated. If it's like that the two of them can easily get away. I don't know how this works but there are downsides around this.

Recent example:
Who's Mr. President? <- it could be that the updaters is different people from the scan group that posted the release entry. Because the title is original with a question mark but their version is not.

Another old title:
Boku to Majonitsuite no Bibouroku <- I remember this title clearly because I have bookmarked another version then (read: it's missing from my list) I have to bookmark it again with the correct version.

And there may be a lot more cases than this that have to be cleared up. It could be one reason of the many causes users feel their wishlists are missing. Actually, I wanted to suggest making a box that we usually find on a blog/website, you know the kind ... that has color and attracts attention like a warning. But if it's too difficult, maybe a simple sentence will suffice.

I don't know how the sentence should be, maybe...

PAY ATTENTION BEFORE ADDING THE TITLES...

or something. But the most important thing is direction so that they really have confirmed everything well. This is my style/habit but I usually do a reverse search.

MAKE SURE BY COPY PASTE THE ORIGINAL TITLE OR VIEW FROM THE AUTHOR'S PAGE...

This can be done for titles that require special characters such as manga/manhwa/manhua. And the rest who use regular characters have to make sure that the special needs in the title: quotes, quotation marks, typos, and etc. Unfortunately we probably won't immediately find the database for the author, so it all depends on searching in the title.

This is not a very big problem as every updaters is different so it can be fixed easily. But it doesn't hurt to try to reduce the burden of entry that must be confirmed. I welcome any suggestions for improvement and maybe adding more.

Quote from tanukischarm

PAY ATTENTION BEFORE ADDING THE TITLES...

Many are lazy and careless. They just add, they don't bother check if they add the correct information or if the entry already existed in database, they don't bother add original name.

I requested merge, delete, edit alot

Worse then duplicate, another type of duplicate is people submit translation of series and think it's original. 🙄 In most cases, just look at art style, look at creator name (if it's not localized), and look at publisher name in that translation version, etc then spend time to search, they will definitely find original one.

But they don't care. They just add.

I'm saying not only about series but also about author and publisher entry.

I also have the same concern as you, but it's just my personal sentiment so I often ignore it haha. And even I'm not free from mistakes. (:

I have no problem if the information inside is incomplete or there are lots of blank fields if it's really hard to find. That's the first exception. The second exception, if we don't know the original title, what the story is about, what is the category, what is the English title for it—don't force it to be a added in my opinion, so as not to provide misinformation. But sometimes there are updaters who use it for scanlation purposes and users need it to be included in their reading list. And again this depends on other updaters, to be more careful in fixing something because I also often see they can change everything at will.

Back to the beginning like I said, I personally won't make a big deal out of it because we have a community that can help each other tho. But if it can be straightened out why not.

Even translator of series was added as as author/artist
They see translation version only list publisher as creator, they add it to author/artist field on series page, or add to associated names on author page. Or they add genres as creator.
They reverse creator' s name order.
Etc.

It's really hard to change habit since they are used to doing that way. Just add. Other things? Don't care.

Sorry for saying off-topic.

All I want to say is there are careless updaters. They can spend their time adding, but don't spend time to pay attention, be careful, check again, etc. It seems really hard for them. They just add and don't bother other things.

Minimize multiple entries is something largely depends on updaters

Yeah, I don't disagree with your opinion. Sorry too because I limited my answer to the original purpose of the thread was created. I'm trying not to want to bring up the updaters' mistakes.

I hope this thread will (as well) be seen by updaters out there to reflect on their actions.