my biggest concern is cagers not being able to see my flashers when I use them. My college buddy, Ritchie has the embedded ones in the tail section of his 1992 Gixxer 750, and you can't see them for crap, not even at night. I rode with him many a times.
But I suppose if you double up, it can be seen. Just makes the cans looks disaportionately large, like battle ship cannons. At least to my eyes, but if it works for you don't what does other people's opinion matter?