Answer:
That probably means that you opened and edited something in one editor than opened it in another so its probably something like that .What program is this?
Explanation:
The most common way I've seen is to have a slide where you have the additional information. It can be phone numbers, email address, websites, books, anything you want to refer to.
People tend to photograph these slides so make sure the information is error free and that you add you own marketing info to the slide as well.
Probably an Operating System like Mac, Linux, or Windows. There may be a type of downloadable software to do this, but may be debatably safe.