I agree with Pizzaman on this, someone with the ability to dupe a key from a picture will not need a key to get into your house.

Something that is somewhat more likely, when you get new keys made pay attention to what you say. I can't tell you how many times i have cut keys for someone and as they are handing me the keys they are telling me that the new keys are for their neighbor. As they are going away for a week or two on vacation and then pay with a check. If i was a thief i now have my own set of keys to your house, i know when you will be gone, and i have your address.

Of course my favorite one was a geezer came into the shop some time before Y2K as he writes a check for his purchase he explains that he is very concerned about the effect of Y2K on financial institutions. He goes on to say that he is going to liquidate several hundred thousand dollars worth of investments and bury the cash in his back yard. I did ask him what time he was planning to go to bed on new years eve and if the address on his check was where he was planning on planting a bunch of money. Amazing.