For one, they are different treasures. The pulls you do for one treasure, does not affect the other. If you split your seal scrolls to both (although you get the Seal Treasure sooner, so you probably used less seal scrolls on it and more free draws), the fact that you got them within pulls of each other is expected.
Two, it's not like a set amount you HAVE to pull before you get a rare as people have repeatedly mentioned getting one from 30-70 pulls or even less. Treat it like refinements, with every pull you have a chance at getting a designated rare, but you'll probably be guaranteed one at 70 pulls.