You can still achieve the symmetry you are after by once again using table lamps and accessories that link the nightstands at odds with each other. When choosing a nightstand, consider the purpose that it serves as much as the aesthetic joy that it brings to the bedroom.
A couple of sconces instead of the traditional bedside lamps, a sparkling floor lamp for a personalized reading nook in the corner, or gorgeous pendants that usher in a transcendental aura; take your pick at your nearest IKEA store and revel in the radiance! Plush rugs and snazzy mirrors add that final oomph that your tasteful, peaceful bedroom needs.
This makes the look a lot more cohesive even if they have completely different finish. A vaguely similar silhouette also gives the room better geometric symmetry making it far more pleasant visually.
If matching style is not something you are able to pull off because you already have a pair of nightstands with one of them being vintage and another modern, then think of a finish that unifies them.