I mean, yeah, I get it, there's a science project with the name "Chell" on it. But Chell could be a nickname for Caroline maybe? But the main reason that I'm suggesting this is because in the ending song, where GLAdOs is talking about how you're not her friend anymore, but then she kinda switched over to referring to Caroline, saying, "When I delete you maybe I'll stop feeling so bad." Kinda made me sus of the whole thing, y'know? Also, it could contribute to how Chell doesn't speak at all.
I get it, this theory has a lot of holes. But let me see what you think? Maybe I could be onto something?