Unfortunately, it is not uncommon for people to enter someone and then assume they are deceased so they can do the work. FamilySearch instructs to not assume anyone is deceased until 110 years after their birth year. A distant cousin entered my 90-yr-old father as deceased and was non-responsive to my requests for him to go in and mark that record as living (as he is very much alive). I had to provide feedback to FamilySearch for them to change the record from deceased to living. It took a month or two, but was corrected.
If she does find a "duplicate" of herself, I recommend she reach out to FamilySearch through the feedback at the bottom of any page (or through the hamburger menu on the app) and ask for the record to be deleted or marked as living. That should clear the block preventing her from being sealed to her parents. Even if she doesn't find a duplicate, feedback to FamilySearch should be able to clear it up. If it was me, I would provide my FamilySearch record number along with the record numbers of my parents and enough information that they can understand what the problem is.