Let’s consider the album U2 - The Best of 1980–1990
MBID: ee0247cd-5a6d-392b-9906-769f87d4ae66
There is 18 Disc ID there.
Does this mean that 17 people entered the TOC incorrectly, not matching the Barcode?
Doesn’t this interfere with MusicBrainz?
Is there any way to fix it automatically?
Here’s some reading material: History:Next Generation Schema/History - MusicBrainz Wiki
I will keep my fingers crossed.
In popular releases there are a lot of junk DiscIDs due to the way pre-NGS there was no concept of separate Releases. As part of the NGS changes every DiscID was attached to every Release in that Release Group. Only post-NGS have we been able to be selective.
This is why you see a “verified” disc ID noted in the annotation of many releases. That way you know which is a real match.
I expect that same list of 18 DiscIDs is also found on many other Releases in the same Release Group.
The list is made up of various things. There will be all the different manufacturers DiscIDs, reissue DiscIDs, and some totally junk ones from CD-Rs.
The Homebrew CD-Rs are easy to spot as these have every track with plus two seconds when compared to something legit.
Trying to fix these takes a lot of experience. DiscIDs are not a one to one match with Releases due to the way manufacturing works. Also algorithms to create the DiscID can change slightly.
For you the user it is not a real problem when trying to find your release, it just means you will be offered more options than you expect. So you have to carefully check between the ones offered. Maybe add a note as to your DiscID on the one that really does match your paperwork.
I will wait until May 13th
so as not to enter my 1000 CD-Audio discs twice.
There are regular updates to the way the database works, but very rare it is anything as drastic as the NGS changes. So don’t worry, you can start on the mission of 1000 CDs. There will be many database updates during the time it will take to add 1000CDs. You’re soon going to get bogged down in the little details on the rear covers of your artworks and trying to read matrix numbers to work out the various differences.
Horror and thriller. 
No need, there is no change in sight that would be as huge as NGS:
Two independent opinions.
Ok I believe.
Sorry for my English, but I don’t fully understand these rules.
Other releases only have one Disc ID.
Main group:
Releases with 14 songs and 1 TOC:
People were picking the first release they noticed and that’s why there’s 18 TOC here?
Because it’s not even random.
Short version - don’t worry about it.
Longer version - Long back in the past there was a less checked way of adding DiscIDs. They came from all kinds of sources. Some of the very oldest database entries have a lot of old mess attached.
Way back in the past, before the big NGS rearranging of the database, there was a very different way of storing Releases and Release Groups. There was not the separate Releases like we have now. So there was no way of adding a single DiscID to one Release.
If you look at the Edit History of those releases with lots of DiscIDs attached you will notice they are all very old Releases. Old database files.
Check the edit histories of those with only a single DiscID and you’ll see these are much newer. After the 2011 NGS changes. And in the newer era where more care was taken about adding DiscIDs.
It was not that people intentionally added 18 wrong DiscIDs, it was because these were all added before 2011 in an era of the database when it was impossible to actually get it right.
Also back in those early days DiscIDs also came from unchecked sources. But that is another tangent of talk.
Actually. A little brighter.
but
if it’s not that important why did you once say that other TOCs shouldn’t be deleted.
You have to be very careful and read the edit history.
I only really actively date from 2017, so have only ever seen the database in the current format. The layout that means we have separate Releases that will match the CD you have in your hand.
The focus now is on making sure you have Release that exactly matches the artwork, barcodes, cat numbers, etc. Maybe even manufacturer who pressed the CD. Often need to cross reference with Discogs to look for other variants.
With the Edit History you have to draw a line. I think it is May 2011. Anything older that this is pre-NGS. So it means any discIDs added before this date was not actually added to this specific release.
I would advise to not yet start deleting anything without more experience. It is confusing as it is common to not actually find the real DiscID in the Edit History. Just due to how old the data is.
This is why some of us encourage people to add a DiscID to the annotation. Even better if it is added along with Matrix Details of the CD they hold in hand.
I only edit and save TOC with a real medium in my hand. Of course I check all the things you mentioned.
Can I delete other TOCs in this case?
Do not be afraid. I’m only asking theoretically.
And the second question:
Can I always at least set the length of the paths in this case?
Check the edit history of the Release you quoted at the start of this thread. You will see I selected some DiscIDs for deletion.
To explain why I picked those is based on looking at the other releases. And most importantly reading the annotation of this release.
I could see this Release has a DiscID that is “verified” by another editor. From looking at this I could compare it with the DiscIDs that were much longer. When flipping back and forth between the disdIds it is clear that every track had two seconds added. So this is clearly a CD-R of a homebrew disc that should not be listed. This is an easy one to be sure that can be deleted.
Real DiscID 65Kxq8ayoWzrbIpAesWCbqEr61c-
Homebrew CD-R 41BNqvhEOGzhMhkSeSMJ0Wx6U6U-
Open both of these in two separate browser tabs and flip back and forth. You can see that two second different is pretty obvious. This is why I deleted it.
What is the DiscID you have in hand? Does the rest of the release match? (cat no, barcode, artwork, etc)
In theory, yes you can delete the obvious bogus discIDs. I’ve spent far too many hours looking at the bad data and now know what is safe to delete. When I first started editing I know the errors I used to make when identifying my releases so I am glad I didn’t delete anything back then. 
And the second question:
Can I always at least set the length of the paths in this case?
“real medium in my hand” - CD, box, cover, physical
If you are 100% certain you have the same release - yes you can. Exact barcode, cat no, artwork matches.
I know the errors I made in my early years that I had to go back to correct. Worth learning a bit more as to how to fully ID a CD first. Especially something that has been repressed so many times like this one. Discogs have 150 variants so it may be that yours is slightly different to the one already listed here.
If you do use the Set Track Lengths option it is a good habit to add some notes about your CD in hand to that edit note. Barcode, Cat No, Matrix, etc.
The release you picked at the start is a good one for an example how some people get confused with small differences.
For some reason there are two Discogs Links added. A UK one and a French one. That French one is incorrect. But the differences are tiny.
UK edition at Discogs
French Edition at Discogs
The differences are VERY subtle.
Look at the rear cover of the English edition. Read right to the very last line of the text. Notice the URL? The French edition is missing the /U2 from the end.
Now look at the CD artwork.
UK CD
French CD
Look at the gap between the head of the person and the title of the CD.
These are the kind of really subtle differences that mean a separate release is required.
I don’t know if length of life will be enough to correct all the mistakes.
The database is going to hopefully outlive us all… by that time CDs will be a historic oddity. Already you can see editors who never finished their mission to document it all. This is why it is a community and we all do out own little bits. It is also why edit notes are so important.
The database will never be perfect. Never be finished. Just improve what you can as you go along, but if it doubt don’t remove things. By the time you have catalogue the first 200 of your CDs you will started to have learnt the skills of being fussy like the rest of us.
It is also why it is best to learn with the obscure stuff. Less variations.
