Maybe U.S cars are different, but both with this & my previous 981 & 987 before it I only ever got & get a chirp if there is something I've overlooked. Examples being, door not shut properly, bonnet not shut properly, glove box not shut, vanity light on sun visor on. Now if your cars chirp in normal locking then I would suggest that when you get the 2nd chirp it's possibly because you've overlooked something along the lines of the above.