When new hires join your organization, they would need to complete several compliance courses quickly. However, there might be an issue where their work account was not ready yet and her SSO credentials were still unavailable at that time. Thus, you created a temporary TalentLMS account for her using her personal email address.
After a while their account is ready and they are able to use their SSO credentials to log in. Since she completed several courses and garnered points from the completed courses, you would like to retain all of them and transfer them to the new account.
In this case, you cannot merge accounts together. What would be possible though, is to change the user's details that have the progress, so that their username and email match the SSO account details. You would need to first delete and permanently delete the new SSO user). Then, they should be able to log in to their existing user account that has their previous progress using SSO credentials.