FortiAuthenticator MAB

Hi. 

We recently imported a list of over 700 MAC-addresses directly into a use group in FortiAuthenticator for a customer for MAB authentication. 
We asked the customer to test this authentication and while doing so they accidentally removed all mac addresses from the group. 
We now have trouble adding all mac addresses to the user group again as you can not import the same mac addresses directly into the group again. 

Is there a more streamlined way to add the mac addresses more than just one at a time now?

Kind regards