I was pretty sure only my Anderson Sheppard had the two buttonholes. But this prompted me to look through all my double breasted jackets just for fun to double check. My suspicions were in fact confirmed. Would that make the double lapel buttonhole a more common British characteristic? Another interesting trait on that same jacket is it has double anchor buttons as well. This is the only time I have encountered this as well.Not all DB jackets have a buttonhole in both lapels, but SB jackets never have them in both.