If they're trading dollar for dollar, that's a wildly skewed trade. The Tangled marquee is older and harder to come by. At a quick glance, the last sold dollar amount on eBay for the Tangled marquee was $750 on 1/26/14. Last sold Frozen marquee on eBay was $252 on 2/16/14, and there are more Frozen marquees on eBay than Tangled, at least at the moment. While I agree that the Tangled prices have fallen a little bit, I disagree that these two pins specifically are "equals" just yet...
I'm definitely no expert on Marquees (Nathan, where are yooou??), but it's such a coveted collection of pins that I think it's possible we could continue to see other Tangled pins fall in price, but the Marquee stay static. I mean, the Up! and Wall-E Marquees still command a LOT of money, and they've been out even longer...
Edit: Also, as an afterthought, when I think of marquees, I know there are loads of people who collect ONLY marquees (i.e. Not Tangled, Frozen, Wall-E, Up! collectors, but JUST marquee collectors) so that also could lead to the rarity and price point of these pins, which further leads me to believe that the price likely won't drop, or if it does, not by much. The pool of people looking for them is more than just movie-specific collectors... does that make sense?