After mamo and u/s showed microcalcifications in wife's breast, had biopsy with benign result. now radiologist wants another biopsy?! is this needed?

I'm sorry, yes: They must not have removed the calcifications, so they didn't really biopsy the area of concern. This sometimes happens; the breast can be confusing terrain, and calcifications are very tiny. If the radiologist is recommending another biopsy, please have it done. I know from experience how uncomfortable it can be, but this is exactly what a good radiologist does. You want to be sure!

Biopsy: There are various reasons why the radiologist might have felt the biopsy was not adequate. Unfortunately, this occasionally happens, and it may only become evident after the pathology report is available. The second biopsy is needed because, although the path was benign, there was not a specific finding that explained the calcifications.