I had a long discussion with a fairly anonymous user, Alice, in the comments on Bob's answer. Within seconds of Alice's latest comment, I migrated the comments to chat as it was getting to be too much. Almost immediately, I saw that Bob appeared in the chatroom and then left almost instantly. Alice never appeared in chat but commented again right after Bob's departure to complain about chatroom migration.
Alice's comments were generally supporting Bob and getting upvotes that could be trying to create the impression the position is more supported, so the behavior was also consistent with sockpuppeting.
While it's not conclusive, if any site mods could see IPs I'm about 75% certain that the Alice account is Bob's sockpuppet. I don't know if that's okay here or how one might report such activity. It's far from certain enough for me to publically out anyone, but I do think it bears looking into.
How should I proceed? I'm fine dropping it if that's the desired outcome too.