Assuming that CPT code can be billed bilaterally, which I have no idea whether it can or not, I will answer as though it can.
First of all, modifier 51 is added by the insurance company on their end, and really does not need to be billed. You can, but it isn't necessary. They will apply the multiple surgical discount, regardless.
Bilateral procedures, in my opinion(and Medicare's), should be billed as follows:
One line of service, one unit of service, with a 50 modifier, and the price should be adjusted to reflect what two units would be, because it could potentially mess up payment application if it isn't. So if you charge $1000 for a 30130, your billing would look like this:
30130-50, one unit, billed amount $2000.
When insurance processes the claim, they will allow/pay 150% of the allowable for 30130.