I'm unclear on your concept. By definition, a Mormon sealing is unequal from a Catholic ceremony. I pledged to my wife "Till death do us part". A Mormon ceremony ensures those people are together, even after they pass.
In a civil ceremony, people can get divorced at any time with no bias from the government. In Catholicism, if you get divorced, you can't get remarried in the Church. That's not equal.
I get the point you're trying to make, but it's nonsensical. You're attempting to create an equality of outcome. My point is that the government cannot discriminate. Right now, that's what they're doing every day they deny people who wish to join equal rights to do so. The government serves to provide people who wish to join their lives a legal framework to do so. A religion serves to provide people who wish to join their lives together a spiritual framework. They each serve a separate and distinct purpose. So...separate the legal from the spiritual.
A government must not only support the majority view, but also respect and defend the rights of the minority. It represents the temporal only; it shouldn't shove those beliefs down the throat of people who find the concept of marriage as anything but one man and one woman offensive. What it should do is to treat everyone equally. That means providing survivor benefits to any couple or group, adoption rights to any couple or group, visitation rights to any couple or group and the ability to dissolve such a union when one or more parties wish it to end.