A small number of new cards from a deck had duplicate #numbers (due) and I don’t know why. I discovered this only when I was studying them a few days later. The behavior was like cards with different subjects interspersed.
I report below 2 behaviors I had with this deck to help diagnose the problem:
I think I never changed the repositioning of the cards in this deck, as I always created the cards in order and changing the positioning was not my concern.
It’s possible that I advanced several cards through AnkiMobile (about 18 cards) and after that I undid the revisions, just to take a look (I know this is not the right method of previewing cards). But I’m pretty sure I did that in another deck and not this one.
I have already repositioned the cards to the correct order according to the creation order. So, my only doubt is: is there any reason for the numbers to be doubled without my action? I want to know what could have happened so I could avoid this problem in the future.
Parent Deck Options:
Insertion order: Sequential
Display order: Deck; Random; Show after revisions; Show after revisions; Review date, then random;
Subdeck Options where this problem occurred:
Insertion order: Sequential
Display order: Deck; Grouping order; Show after revisions; Show after revisions; Review date, then random;
The next due number is synced. If you forget to sync at the start or end of a session, and have added cards on one device, you can end up with a series of numbers being repeated. Use check database to fix the current count.
I understand, I synchronize everything very frequently, I even have an automatic synchronization addon. I leave “synchronize on entry/exit” turned on both on the computer and on AnkiMobile. I’m going to be even more careful with syncs now.
As for checking the database, I carried out the check to try to solve the problem with the duplicate positioning number, but it didn’t solve it. I had to manually reposition it.
But, just to make another question clear to me:
In this hypothetical example:
“I logged into Anki Computer > added a card > left without synchronizing > performed reviews on AnkiMobile and synchronized > logged back into Anki Computer”=> After logging back into Anki Computer, the database must be checked first to perform a new synchronization on the computer? Or does this order not matter?
Check database isn’t going to resposition any of your cards. Anki doesn’t know if maybe you wanted them like that, so it wouldn’t change them without asking you. But the database check will refresh what the correct “bottom of the queue” number is on this device, which will then sync to the other device.
You should be syncing at the beginning and the end of using each device (the start and end of each study session is another great way to think of it). That’s the only way to make sure you’re always working with the most updated data. If you don’t do that, and you make a change one one device that is not mergeable, then you might have to force-sync in one direction, and lose the changes/reviews/updates on the other device. Yes, there are often ways to save things and re-merge them, but it’s an unnecessary and completely avoidable hurdle to put up for yourself.
Remember that you’re not syncing the devices directly with each other – you’re syncing each of them with AnkiWeb. If you let them get out of sync, you aren’t guaranteed to be fully matching again until you’ve synced three times (computer / mobile / computer, or vice versa).
In your example – no, the database doesn’t necessarily need to be checked, because you only added notes/created cards on one device. But you still should have synced when you left the Computer, when you arrived at Mobile, and when you arrived back at the Computer.