DT tag is definitely required for spammers cheater multi accounts like this. So give DT1, DT2 tag as soon as possible (thanks).
Got any proof that this user pulled off any shady stuff or violated any rules with his alternate account?
All I can see is that andrew_788 took part in some bounties nearly five years ago but has remained inactive ever since. I do not think that deserves a tag from DT members, even if they are confirmed to be alt accounts.