I've watched the Dome/Zooz version with a z-wave sniffer and the hub usually ends up sending the command multiple times because the device takes too long to respond. The heavier the z-wave traffic at the time, the worse the problem is.
In theory that shouldn't be a problem because the device should only execute the commands it acknowledges, but due to either a timing issue or an issue with the device it occasionally executes more than one of the commands.
SmartThings has the same problem and based on the complaints I've seen it tends to happen more often with the Neo version then the Dome/Zooz version. The Neo device isn't identical to the Dome/Zooz siren so there might be other ways to improve the reliability. I have a few ideas which I'll be testing when I write the official ST handler for it within the next few weeks.
