No, I have not see ANY ankle-holster with a mag pouch (which sounds like a great idea gun & mags are not TOO heavy) but I recently saw this company that advertises actual ankle-carry mag "pouches" -- which I have not seen anyone else offering before, either:
http://www.bluestonesafety.com/products/holsters/
...both these AND their actual ankle-holsters look quite comfortable, with that sheepskin fleece AND they look like better designed holsters than the Uncle Mike's Sidekick Ankle holsters I presently use.
Personally, I use a 2nd ankle holster on the opposite ankle for spare magazines carry!
Maybe you could ask Bluestone if they could start offering what you're looking for.
Good luck...