When we are out of the adult strength Hep B and an adult needs a vaccination, we use two 0.5 ml vials of Recombivax B, pediatric/adolescent strength (5mcg/0.5ml), in one 1.0 ml injection so that the adult patient gets the proper adult dose of 10mcg. Billing for this has always been a challenge. If we bill 90744x2 some insurance companies deny the claim as an age mismatch. If we bill 90746 the claim may deny because the NDC does not match. What is the correct way to code this?