Nuss procedure

My surgeon sometimes puts two bars in when doing a nuss procedure. He is using the same incision but thinks he should be able to bill CPT 21743 x 2. I would agree with him if he were making two seperate incisions. He is making an incision on both sides of the chest but he would do that when inserting one bar. Also, when he removes two bars he feels he is justified in billing CPT 20680 x2. The stabilizer for one bar is on the right and the stabilizer for the 2nd bar is on the left.

Thank you for any advice you can give.

Nuss procedure