I would want to know what it means to date them as a couple. What if you form a strong relationship with one, but not the other -- would that be fine, or are they a package deal only? If the latter, that sort of thing very rarely seems to go well.
Good advice here: http://www.morethantwo.com/coupledating.html
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.