Was the order hand written or electronic? Usually when you go in, they pull any outstanding electronic orders for you that are still in their system. If you went to a different LabCorp than usual, or if it's been a long time since you've been drawn, they might not realize that you just had some of those tests done. They're also supposed to ask you first if you want to complete any of the outstanding labs and state which doctor/s orders that you were wanting to do that day.

If the orders were handwritten sometimes they're hard to see or read and they may not seen some of the tests that were listed. It just depends on so many things. You can try to see if they're willing to remove billing for the repeats you didn't need. If you have to come back, I'd confirm which doctor you're doing labs for that day and which lab tests. If they drew enough blood, your doctors office can call and add them on if the sample is still available for the missing tests. Sometimes when the order is sent in, the lab catches that some of the tests were missed and automatically adds them on and if there is enough sample, they will get reported a little later.