It isn't
Called a Barber's Notch that is, we have so far only found it to be named a Hollow Point or a Hollow Notch the only references to Barber's notch are new...
Keeping that in mind and looking at different points for razors, it might be just another point design :)
PS anyone that finds a pre 1970's reference to the name "Barber's Notch" like in old advertising etc: that would really be cool... and please post it up... Collector books, are not a solid source, as they basically have no more weight then what we would post here...