I have no doubt your intentions are good and it is clear you spent too much time in this investigation. But unfortunately proofs are not solid enough.

We saw similar cases before and the common pretexts are:
- for sending tokens to each other: "we are friends"
- for using the same TG/FB/twitter account: "I copied someone else's report and forgot to edit the account id.

It would be better to report them to bounties managers, it is their job to check whether they are alts or not.