As a result of listening to a lot of James Jamerson recently, I've been trying to play several songs with just one finger. Not sure if David “Hooks” Williams (the original bassist on this track) used one or two, but I would guess one. You can get a fatter tone, a more even sound, and it grooves harder... but it's also harder to execute.
I heard Mike League (bassist for Snarky Puppy) say that it’s similar to when a drummer plays a sixteenth-note hi-hat pattern with one hand or two. Neither is right—they just produce different feels.
Enjoy!