No - you should not create a separate registration unless there is a difference in the songwriting splits from the original registration.
In order for someone to cover one of your songs, they must obtain the proper license to do so. You will be owed the publishing royalties from their version of your song, and their earnings would come from the master recording (you can learn more about the difference here).
It is important that you add the ISRC of their version of the song to your existing registration from the "songs" page in your account. If you click on the song title, you will be brought to that song's page, where you will have the option to add additional recordings.
It is always a good idea to let us know over the chat box that you have added new ISRC's to your songs so that we can review and make sure it was attached properly.