We often get questions from our customers about keying their locks alike. There are a few things to remember about keying. First, not all brands of door hardware can be keyed alike. The best thing is to be consistent with the brand of door hardware you choose throughout your home. I say this for two reasons, we can key them alike and the finish will be consistent. Different Door Knob manufacturers may call their finishes the same thing- like oil rubbed bronze- but there may be a slight difference in the finish. Not a big deal really, unless the you have a doorknob of one manufacturer right next to one from another.
If you have existing locks that you will keep and want to get new locks to use the same key, you'll probably need to have locksmith come out to your home and key the new locks alike, the risk you run is that the existing locks use a different keyway than the Door Knobs you purchase.
Direct door hardware offers Door Knobs and locksets from several manufacturers, and as much as we'd like them too, they cannot be keyed alike. So remember this as you shop for door hardware. If you want all your keyed locks to be keyed to the same key... make sure all of your locks, deadbolts and handlesets are the same brand. Interiror Door Knobs like passage and privacy sets don't matter as they are not keyed.
Oh, and most of the time your keyeing will be free!