User blog comment:TVthePunisher/Translations of Interviews in MASKED - Past and Future of Bleach?/@comment-1906999-20100815223104

Uryuu and Renji could know them, but they don't need to. They could just be reacting that Szrayel would be experimenting on other people. I don't know about you guys, but if I saw people hanging from the roof of a lab, I would be surprised whether I knew them or not.

I think it could be Dordonii and Cirucci. The left one looks like it could be female and is wearing boots, which would be Cirucci, and the right one is wearing pants, not a robe, and Dordonii wore baggy pants. Like Godisme said, it's impossible to prove, this would be my best guess.