I was not able to replicate this problem but this is what two users are reporting. When they go to [Share] a document/file uploaded in SharePoint 2016 Document Library, within the Share section they type in the user's username and it gives them 2 x same identical username but on different domain.
However, there is only ONE such usser account in the Domain and there is no others in other domains.I have reset the cach files on the client's browsers but same result.
Please advise.