Magnezone does not have 2 differen Hidden Powers.
Hidden Power Water and Hidden Power Fire are the top two Magnezone can make good use with.
Magnezone like all Pokemon can get upto 17 Hidden Power Types
(Hidden Power Fairy does not exist)
Only a special combinations of IVs will get you Hidden Power, or HP for short, fire.
The IVs for HP Fire is as follows :
These are the maximum IVs but however they can be lowered.
EG. 31/30/31/30/31/30 can also be : 21/24/19/28/1/12