[VonBarb.]

I've only read accounts mentionning the R4Ms were fired in 24 rockets salvos. Judging by the size of just one rocket and the relative lack of accuracy, I doubt firing jsut a pair at a time would have had any measurable effect anyway.
According to Galland himself, bombers shot down from direct hits by salvos of 24 were nothing but lucky shots, so I can't imagine why they'd have wanted to divide their chances by 12...

Cheers

Nico