Two charges for each crown. Why?

unfortunately,  insurances do not pay what they use to and if you elect to get metal free crowns .   Ceramic substrates , zirconia crowns are considered an upgrade.   As a result , the office can charge you additional fees and what they give you has to match what is billed to the insurance. 

Hi, Barbara. I am assuming your insurance is a PPO insurance. These insurances do require itemizing everything into a crown and the insurance codes require sometimes 2 entries on charging crowns.
You might want to ask your dental office this question as I am sure they are more than willing to help.

Your dentist likely has to itemize the fees for your insurance. Insurance companies are all moving towards less reimbursement for dental care, and may only reimburse the portion attributed to a cheaper type of crown. I'm in Canada, so I don't know all the ups and downs of insurance in the US, but here we have to itemize the crown and the lab bill separately.