Can Red Merle Border Collies have black noses?

No they cannot. Genetically a red merle is a dog that is chocolate/liver dilute plus the merle modifier. read more

I haven't found a single instance of it happening anywhere except with my new puppy. read more

All merles may have blue or partially blue eyes, and pink or partially pink noses. Merle can be completely hidden by recessive red, as recessive red dogs can't make eumelanin pigment and merle only affects eumelanin. A recessive red merle is known as a phantom merle. read more

In the red color, the chemical is a pigment called eumelanin. This is one of a group of pigments, the melanins, which cause color in animal skin, hair, and feathers. It is responsible for very dark brown or black color. All Border Collies have in their hair a red version of melanin, called phaeomelanin. read more

A few years ago, all the Border Collies in a sheepdog trial would have been black and white or tricolor. read more