yes, it could be and was done....and when your the only one shooting a 50, it's hard to blame enemy fire <red face>
It was also common for bombers flying in formation to accidentally shoot one another
Friendly fire with 109's and 190's making runs at you was of course an for gone conclusion especially at day over Germany with the Luftwaffe at its strongest in 1943 and '44. The USAAF B-17 8thAF Bomb groups flying over Germany had formations set up to give as complete a coverage as possible around the formations.
IIRC clearly, the somber narrator from John Ford's "Memphis Belle" speaks with the combat camera swinging all around looking at the surrounding bombers during this epic 25th mission for the Memphis Belle,... stated that.....
"the formation is the bombers best defense against enemy fighters.
The planes are deployed to uncover ever gun.
Stepped up,...and down.
Echeloned to the right, ...and left.
Arranged to overcome the dangers of gunners firing into friendly ships.
Arranged so concentrated cones of fire from the Caliber .50 machine-guns cover the sky...
for a thousand yards in every direction."
One of the waist gunners in the "Belle" was said to have two confirmed Me-109's with his single .50Browning, probably by concentrating more intently on his lead and on killing the enemy fighter than being 100% concerned on where the rounds are going beyond the 350 mph or even 550mph target when passing down your side going bow to stern.
This was "The new Front",..... the Air Front!