It was a confusing situation, quite frankly. Having a subcontractor the agency identified put through the GC Strategies contract meant that the terms and conditions of the contract with GC Strategies applied, meaning they got their finder's fee for having a subcontractor even though it was the agency that identified the resource.
Ultimately, to the nub your question, I think it cost more because they shouldn't have had to pay for GC Strategies' portion of that. They could have just paid KPMG for it if they had put a contract directly in place with KPMG.