We don't do this position often, but has been helpful if they both are upset at the same time. As they fall asleep, their latches get lazy and teeth get involved, so I do try to only nurse one to sleep at a time.
The unspoken benefit of nursing 2 babies at a time: they create great cleavage. Push up bras got nothing on tandem nursing. However, due to limited lap space and balance, it's usually only done at home. This one was taken with my camera phone.