If you think about particles as objects in the configuration space, them you don't really talk about two or more particles. One point in the configuration space (being it the origin or any other point) represents one (abstract) object. With one object only, the notion of "meeting" does not make sense. And that applies to both classical and quantum mechanics.
On the other hand, if you think of x1 and x2 as positions of two particles, than they meet each other everywhere on the diagonal x1=x2 through the origin, not only at the origin x1=0, x2=0.