Unable to match transaction based on Meta Data.
All Supported DevTest releases.
Created a VS using REST Data Protocol DPH for your REST calls with URLPARM0=accounts and expect a transaction match with different values sent in the headers but getting the same transaction match.
Request headers are not going to be created as arguments with REST DATA Protocol.
Refer to section "Request Data Manager Data Protocol" in the documentation of the DevTest release you are running.