The only thing that would be separate is the term used to describe it. For me, it's a languge issues, not a civil rights issue. And besides, all laws "discriminate" against somebody.
Unfortunately, this is not the case. In New Jersey, a state that has civil unions, a number of companies and insurers are playing "language" games, refusing to offer benefits to gay partners because they're not married -- merely civilly united. They're not supposed to discriminate that way, but the fact that there's no federal law means it's in businesses' best interest to try and see if they can get away with it.
Separate but equal has literally
always failed the "equal" test.