Just had bathroom remodeled with a retro look. My existing knobs in house are round brass handles with a rosette. The bathroom sink cabinet has small oval crystal knobs. I want to replace the door knob with an oval crystal knob. Do both sides of the door have to have the same knob? Can I leave the existing brass knob on the outside of the door and have the oval crystal knob on the inside of the door so that when the door is closed all the knobs in the bathroom are the same style? And it needs to lock.