also watch the constipation with doubling iron supplements.
Too much iron is also really not good for you, you can overdose, I can't remember what exactly it does but I know it's not good. I wouldn't be doing it unless under close supervision by a doctor.
I was really low on iron a month ago but couldn't double my supplements as they backed me up something shocking and made me get haemaroids (TMI) which flared up badly.
Make sure you are also getting heaps of Vitamin C into you as well as it aids Iron absorbtion I find it will also make me some somewhat less backed up as well.