(click pictures to enlarge)
These are two car alarm campaigns that use the same creative approach to explain their product's benefit. ABT (bottom two pictures) first executed the concept back in 2007. There is nothing wrong with the concept, however, the art direction is just plain weak. Cobra (top two pictures) created their campaign in mid 2008 with a similar concept. In my opinion, Cobra's ads are better put together, and the message is delivered effectively. I like how Cobra's ads build suspense. You can imagine in your head what would happen if the thief continued what he was doing.
This is a common case in advertising. Create a nice concept and it's almost guaranteed that someone else will try and do what you are doing. Sometimes you'll come out on top, and sometimes you will look like an idiot for trying. Either way, it's best to just do your own thing and avoid the situation all together.