The formation the pair were flying in would be of interest. If they were flying at the same height (quite likely), and both spotted the powerlines almost simultaneously - and the bloke on the right banked left, and the bloke on the left banked right, whilst both were distracted by concentrating on the power lines ... then that would be a possible MAC scenario.
However, it does seem strange that two highly-experienced older blokes would each be unaware of his mates position.
Then again, I notice that the older people get, the more they tend to get fixated on a single looming problem, and neglect awareness of accompanying developing situations, that are obvious to younger people.