I believe that the contracted one will send the results directly to DODMERB and you won't be able to see them or retest if you find something is off...
I had a remedial to do a TSH test to test my levels (remedial for hypothyroidism) and after I read in my DODMERB letter (you will see that in your correspondence) that if I chose to do it with them I would not be able to know the results I decided to do it with my own doc...the tests are the same is just that. My test costed me about 15 bucks which is nothing so take that into consideration if yours will cost a lot.. They won't reimburse if you choose your provider.
I suggest you check your DODMERB letter to see your instructions as to how to do this and if doing it through your own service provider is an option I would do it like that...
PD: I was cleared for my hypothyroidism after sending remedials so no problem using my own lab or Doc.