It is very common for there to be multiple recordings of the same composition (remixes, covers, etc.). Unless the splits have changed, you should not make a separate registration for that version of the song.
When we ask you to link recordings to your songs, we are looking to obtain the ISRC. ISRC stands for International Standard Recording Code. It is a unique code that represents the identity of your recording. In order to properly register, map, and collect royalties for a song. This means that each recording would have it's own ISRC even when they are the same song.
In order to add an additional recording to a song that is registered, you will need to navigate to the 'Songs' page in the menu. Then, you will click on the title of the song. In the upper right hand corner, you will see a red button that will allow you to add another recording.
If you have trouble with this, feel free to use the chat box in the lower right hand corner of the screen!