It does indeed sound a bit excessive to charge for both the repairmen.  If you have a relationship with the repair people call them.  Let them know that you have used them before and that you rely on their good service and their honesty and that this job did not require two people to service it and why are you being charged for two people.  See what they say.  Most places will take some money off the bill for you just to keep you as a customer and for good will purposes. And if they don't you have the option to not pay one of the charges and wait until they sue you for it, which will happen.  Then you can dispute it before a judge.  Good luck.