Duplicate mailboxes

We discovered few users having mailboxes on both ONprem (2010) and Online. Get-mailbox, get-recipient, stats work on both the onprem & online. get-recipient shows user mailbox even the EMC search shows user mailbox.
MSOLuser gives account inf and licenses assigned.
From get-mailboxstat -include move history we have logs that these mailboxes are moved to online. The onprem mailbox stat shows very few or no emails.
Users are having issues with autodiscover. Please advise with the resolution steps for this use case.
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Vasil Michev (MVP)Commented:
Ditch the on-prem one, as you have already (planned to) moved it, by converting it to mail-enabled user. You can export the messages and send the pst to the user.

If you can repro this or have detailed steps to describe what happened, open a ticket with Microsoft as they were looking for examples of such behavior (well looking to confirm it, as it seems people run into this situation occasionally but no one seems to be able to reproduce this reliably yet).

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
o365AdmAuthor Commented:
Thank you again Vasil.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Office 365

From novice to tech pro — start learning today.