Theoretically, you don't have to amend if the amendment has no change to your refund/tax due. I recommend however, that you do amend showing zero tax difference and send a copy of 1099-B. The IRS does have your 1099-B and may assume no basis if it's not reported; which will trigger summer correspondence from them asking about for 1099-B transaction.
Your other option is not to amend and wait for the notice. Once you receive it, just respond to it with the copy of the 1099-B...There are no tax consequence since your bottom line is not affected.
