Not really useful info, but i've known 5 people over the years that did both.
One was a military helicopter pilot who got a fixed wing PPL, another was a BA 747 captain who did the PPL(H), but i think he just did it just to get the license and didnt carry on. The third was an ATPL(H) who was sick to death of the North sea and converted to fixed wing and the other two were PPL's who both went fixed wing to heli's.