If you read Grizzlors explanation you would see 
that these are production cels. It's pretty hard 
to make a fan cel and make it look faded and aged 
like a real 20 year old cel.

Personally I think that reproductions would be 
more "perfect", like the perfect Lion-O shots on 
YJ right now. Not that that Mummra isn't perfect 
though ^_~