+20%, +20% double enchanted axe

I saw someone selling a double +20% enchantment axe(req 3 blue). One 20% from inherent, one from mod.

Question 1: do the 20% enchantments stack?
Question 2: how can i get an axe with 20% enchantment

http://www.guildwarsguru.com/forum/s...ad.php?t=94921