Hi Chris,

We recommend, first of all, identifying the source of the duplication and eliminating it. Then we recommend transferring all the records associated with one of the duplicates to the other and deleting when you are 100% satisfied you've captured everything. This will likely involve the use of Course completion uploads. 

Please note there is no reliable method to merge accounts & we are not currently developing any due to the inherently risky nature of the issue when it comes to user data integrity. I believe there are some 3rd party account-merge plugins available but in our view they will break your site sooner or later.

regards,

George.