I found these photos at a fleamarket. They don’t have a date, but CDV-photos were used between around 1860 and 1915 in Germany.
Also fun fact: The two kids could very well have been boys. It was customary at that time to dress up boys in dresses for photos. My family has a photo of my great grandfather as a young boy in a white dress.
Yes, I paid 3€ per photo. I saw this type of picture being sold for up to 70€ on the internet.