In my opinion it will not consider bounty abuse if users joined different campaign. But there is question about social media links and eth address. If socia media and eth address totally different than it should not called abuse. And I don't think it's necessary to use alt account for different bounty. Sometimes it's depend on bounty managers, he might be reject or accept. As hilariousetc said he have joined two different signature, I don't think it's abuse. But on social media campaign if different from signature. You should move it on Reputation to get right answers.