I got mine a while ago but I chose 2 pairs from 2 different designer ranges. 1 was red or dead reading glasses and the others were sunglasses (can't remember range name)

So long as both are marked in the same "2 for" price range it's ok. If one pair is in the "2 for $249" and the other "2 for $199" I think they'll let you get them but charge the higher rate.

Be careful with additional charges. I ended up paying over $600 for 2 pairs. Polarized lenses on my sunnies and anti glare on reading (because I look at a computer all day) aren't covered in the basic pricing.

Hope some of that helps, and it's not completely off the mark