Many years ago I encountered cheap knock-off network cards¹ that had default MACs in the range of a big known name brand, and as far as I know it wasn't some cr

Many years ago I encountered cheap knock-off network cards¹ that had default MACs in the range of a big known name brand, and as far as I know it wasn't some cross-branding/affiliate/other deal. So yes, there has been and no doubt still is. [1] in fact, back in my student days most NICs I had were cheap knock-off versions, the "real" things were not the inexpensive items they are today. This predates it being common to have one built into your motherboard, even more expensive ones, by some time.