There are a lot of different types of scammers active in bounty section. Protecting our IDs from them seems to be a challenge. Like you, I have had such a problem. A bounty cheater named DeXiam used my details to participate Butter Swap bounty and stolen my work in Amepay bounty. I put a negative trust on his profile. But since I am not a DT member, he does not care about it.

Proof:
Amepay bounty:
I posted my week 1 report on Oct 7
https://bitcointalk.org/index.php?topic=5279528.msg55329077#msg55329077.
Scammer copied my report and posted on bounty thread https://bitcointalk.org/index.php?topic=5279528.msg55334456#msg55334456.
Archive: https://archive.st/archive/2020/10/bitcointalk.org/i0s4/bitcointalk.org/index.html

Butter Swap bounty:
My week 1 report link:
https://bitcointalk.org/index.php?topic=5280065.msg55348152#msg55348152

Scammer's week 1 report link:
https://bitcointalk.org/index.php?topic=5280065.msg55353913#msg55353913

Then I put a negative trust on his profile but he still doesn't stop.
.