I don't know what relays they use. I just poked around, and found where relays are listed. No, they do not share the same relays. It looks like the relays can be changed. Can more than one relay be used at a time?
Discussion
Yeah you want to make sure all your relays are the same between your clients and yes you can have as many relays online as you want, but too many can drain your battery faster on your phone… on my personal npub, I usually have 13 running