Ipsy is actually pretty good about things like that, I've never (in three years or so) received duplicate shades of the same product on one account. If they want to send me the burgundy liner this month I'm okay with that, the bronze one I got last month was nice so its not a big deal to me. I remember trading like crazy to get both and/or multiple shades of an item they sent out (the Circus nail polishes, Zoya polishes, the Pacifica rollerballs, eyeshadow quads, the glam glosses) but now Ipsy is more likely to send me the 'other' shade in the coming months so I just wait to receive it or re-activate my second account.
And if Ipsy does slip up and make a mistake, they're usually pretty good about making it right and sending something else to you.