You can but it's a waste of gold because the passive that increases your crit damage is wasted in the 2nd IE. You also will have built no attack speed items (apart from say Berserker's Greaves) so although you'll have high damage, your Q cooldown will remain too high and you will miss out on the passives from Phantom Dancer and Statikk Shiv.
:^) :^) :^)
Then build 6 IE