Who is to say whether they've been re-ground after code stamping.
Also - with a dial gauge we can double check the cam for possible grinding mistakes done by lobe grinder.
To what I've been told, it's not totally unheard of having differences in duartion/lobe separation between cams in a same camshaft. Camshafts are mass products, mistakes do happen.
I went through my re-ground Toyota cam. Class product. Everything was within specifications. Now I sleep better.