I believe the double keys are against code most places, so the lock kits may not contain them.
But you can purchase double keys independently and have them re-keyed.
I have double key locks on all exterior doors that have glass panels. For safety, I have a separate key made for each lock. As long as we're home, the key stays in the lock. I put cup hooks in the door trim, out of sight, where we hang the key when were leaving the house. It also means that's where the key is if we come home and enter through the garage and forget the put the key back in the lock.
ETA: May be nerdy, but I also have a small wrecking bar near at least one window in every room and chain ladders under the windows in the upstairs bedrooms.
This post was edited on 1/12 at 2:55 pm