It’s not about surname.
And in the finer vagaries of qualitative reviews, it isnt “mixed” alone that offers anything. Its when a kid with that duality (or more) offers the campus community some unique perspective. As always, an applicant needs to show that, in his app, not just check some box or state it.
There’s less “pigeonholing” and more reliance on (or adherence to?) what a candidate actually shows in his app, that the college looks for, what comes across. Or not. The big Not. Put your mental efforts into the right aspects.