Updates showing wrong apple ID

Question

I am NOT an end user.  I am a technical support and phone administrator at my place of employment.  I have searched this problem, but it seems that most people are receiving it under different circumstances than I am.
We have approximately 20 lines with AT&T that are iPhones.  I am regularly upgrading iPhones as upgrades become available to my end users or when they are having issues with their old phone.  When the new phone comes in, I encrypt backup their old phone to my laptop in iTunes so that I can restore it to their new phone.  I generally will backup their apps and have them put in their Apple ID if they want their apps restored.
Once I'm done with the process, I deauthorize their phone from iTunes on my laptop and I remove their backup, so that it doesn't interfere at all with my own iPhone.
I have one user who received an upgrade about a month ago.  I followed the same process that I always follow - did an encrypted backup to my laptop, had him punch in his apple ID password to backup his apps, backed everything up, then restored it to his new phone.  I had NO other backups or authorized devices in iTunes (apart from my own).
When he tries to run updates to apps (via App Store > Updates), it is prompting him to enter the password for an Apple ID that belongs to one of my OTHER users.  It does NOT do this when he downloads new apps.  His Apple ID is correct in both iCloud settings and iTunes settings.  There appears to be "nothing" on his brand new phone linking him to the other person's Apple ID, EXCEPT when he is running Updates on his apps.
Why is this Apple ID lingering in there when it has had ZERO association with this phone except for having been connected to the same laptop and iTunes as another user's phone (even though the other user's backup and authorization has been removed from the laptop?).
Today, I logged onto a different computer which has never had iTunes installed.  I installed iTunes, ran an encrypted backup on his phone, then factory reset his phone and restored the encrypted backup to his phone.  I am hoping that this resolves the problem, but when I go to App Store > Purchased > Not on this iPhone, it still seems to show apps that other people have downloaded (including apps that I have downloaded on my own phone).  I don't understand why other people's data and past purchase/download history is lingering on phones and Apple ID's that are not attached to these phones and Apple ID's.

Answer 1

There is a definitely a defect here and I think I know what the problem might be. I had experienced this issue with 8.1.3 on an iPhone 5 as well.   I recently needed to restore a replacement (new) iPhone 5 from a backup that I maintain on a MacBook. In addition to the backup of my phone,  there is also a backup for my wife's phone as well.  The backup from which I restored my phone, was a few months old, so naturally there were several apps that needed to be updated. I can't remember if I had explictly started the appstore, or if an auto-update kicked in,  but I was prompted for the password for my wife's user id. Which I thought was odd, because I knew that my credentials were correctly set in for the appstore settings. I had somewhere on the order of 20 apps that needed updating and I had tried to download a couple of new apps to see if I could isolate it to the app update process vs. a new app download process. At first it seemed I was unable to download anything, but a little later on I notice the new apps that I had chose to download had been done so successfully. I then tried to update a couple more apps, which I was able to do. So the symptom of nothing downloading is attributable to network flakiness either for my WiFi or with Comcast.  But the prompting problem remained and there were a small number of apps that I couldn't download using my own credentials.  So I double checked my wife's older iPhone 4 and I found that the apps for which I was being prompted, were on her phone as well.  I then found that I could delete those apps and just download them again, rather than try to update and I was able to get back to normal.
My wife isn't the most diligent about keeping her phone up to date with the latest version of apps (no  auto-update turned on), particularly for apps that she uses infrequently or never.  But when I looked on my phone, I saw that the apps that I had been unable to update were restored to be from older versions from her phone, and not newer updated ones that I had actually backed up.
At some point in the iTunes backup/restore process data was either overwritten or read incorrectly. I'm guessing that the problem is on the restore side, because I had backed up my phone more recently than when my wife's phone had been backed up.  I was lucky that we only had a small overlap in the number of apps, but I can imagine in scenario like that experienced by UnixChick, where there might be many more overlapping apps for many more phones, the problem can be costly from a support perspective.
So the workaround will be for each of the users to try to update as many apps as possible and delete the ones for which they are being prompted with incorrect credentials and download those anew.  I can imagine that if the any of apps don't do a very good job of ensuring that state is persisted remotely, that there could be some data loss as well.  One thing I am uncertain about is if any application data from the app versions that were restored from my wife's backup was surfaced on my phone. Now I doubt that would happen, but if it were to happen, that could be a potential security problem, were any of that data to be sensitive.