So did the Air Force base security teams using the XM706E2 Cadillac Gage V-100 that had a pair of M60s mounted. There were also turret versions with twin Browning .30 or 7.62mm MGs.
The problem is that there aren't yet right-side feed mechanisms [top covers] for the M240G and M249 SAW. The M60 was adaptable to such twin-gun configurations based on the work that had been done for use as the M60D helicopter armament applications, though I don't know if any actually fed from the right side or not. But the M73/M219 7.62 coax machineguns used in our tanks could, though they were no more reliable feeding from the right side than from the left.
So did the Air Force base security teams using the XM706E2 Cadillac Gage V-100 that had a pair of M60s mounted. There were also turret versions with twin Browning .30 or 7.62mm MGs.