If the facility bills separately for the Technical Component, then the CMS1500 should show up only 77057 with 26 modifier for the professional component. But, if there is no separate billing arrangement between the Technical and professional components, we bill the code without any modifier which will fetch payment for both technical & Prof components.
Ideally, billing 77057 without a modifier on the 1st line and billing the same code with 26 modifier on the 2nd line is NOT correct.
Just to remind you, you may have to make sure you use to right code depending upon the type of mammogram performed. If it was a digital mammogram taken, you bill a G code (G0202-G0206). If it was a Film Mammogram, it would be a 7705x code.
Good Luck.