Very many thanks for the replies.
I see that I evidently did not express myself correctly. My reference to the 'breather tube', was to the 1/2" tube on the side of the rocker cover, not to the oil filler.
I the hope that pictures are worth more than 1'000 (misleading) words, I attach a couple of photos showing the two breather tube outlets on the two rocker covers.
Sorry for the confusion.