I really do hope its him :)
We do use middle names, but when there is a "-son" at the end of it its usually a last name.
I just realised that I've made as spelling mistake on Mats/Mattis last name, I've corrected it in the last post. It now reads Jansson. Which more than likely means that Mattis fathers name was Jan.
Let me know if you need any further help and I'll see what I can do.