I'd venture a wild guess that DPR knew the two were the same :) He paid off friendlychemist "indirectly" but also communicated that he wouldn't mind extreme measures to make him disappear shall this occur again.
If you keep reading, the document later details that DPR contacted this "redandwhite" person, who he contracted to kill the other person, regarding false identifications. That seems to add some doubt to your hypothesis, or at least complicates things.
It appears to fit with his persona of being a ruthless pirate, and the language also fits the big talk idea. He was paying for the problem to disappear, and he knew that, but he talked it up for fun.
However, he went too far into his fantasy, and not too smartly, and he'll pay for it.