I get this message, when I export a graphic file from print mode. It has been like this for a long time, but I always forgot to mention it. Should be translated into German as well.
Since the default name of a slice export is “Slice 1,” if you already have an exported slice in your destination folder, you will get this message unless you rename your slice.
Derrek, this topic is about tranlation and not about the reason for this message.
My mistake. 
In theory these strings should already be being picked for translation, so we’ll look into this further.