Runes for Gloves of Madness
If I understood you right, you’ve tried to upgrade the gloves with the same rune 3 times?
The gloves already have the Mad King rune on them. Runes don’t stack on the same piece of armor. The benefits it lists are the potential benefits from having the runeset on multiple pieces of your armor. To get all the benefits, you need to have a Mad King rune on your helmet, shoulders, chestpiece, gloves, pants, and boots.
This is the wiki page for runes, which provides more information on what runes are and how they work.
By Ogden’s hammer, what savings!