I have ADHD and a generally bad memory, so I have a habit of buying things and forgetting I did. Compounded by having everything out of view, in a box, for ages.
Naturally I bought a few more fountain pens while the rest were still packed. Fortunately I didn't duplicate anything.
Finding a lot of stuff I didn't know I had, and a lot more stuff I couldn't even identify at first. I had to do a few hours of research last night to figure out what some of my pens are.