purcell prusik as a tether while sport climbing

I know the question of PAS of some sort vs slings vs a prusik etc. comes up too often. I have no intention of bringing this debate up again.

My question relates to cleaning a sport route and how people tether themselves to the two anchors while setting up for a rappel. If you use a prusik do you carry two as you would with slings or is there something I'm missing?

Thanks

A purcell prussik has 2 "ears" so bring an extra 'biner and clip one to each bolt.

Thanks. I thought that was the case, but couldn't find any discussion of using them this way.