I clicked on some of them, and most have fewer than 20 recorded instances in over 100 years. I guess it happens sometimes, but it's really not comparable to the prevalence of names like Ed, Jo, Bo etc (which aren't always contractions). The most common two letter name in France is probably something like Li or Ng.

Edit: Funny observation - when you use the system that's linked to try and look up the public records, it won't even let you search for names with less than two letters.