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.
EDIT: Or he was watching too much breaking bad and beginning to assume Heisenberg's characteristics after feeling invincible for earning $80MM
However, he went too far into his fantasy, and not too smartly, and he'll pay for it.