This is strange. In most cases, including my Pi, when booting Raspbian there's just one Raspberry Pi logo at the top of the screen. However, take a look at this:
I've seen this once before somewhere else, but with three raspberries. I assumed it was because it was a Pi 3 (3 raspberries=Pi3), but now this one has four, so it can't be that.
What's with the extra Pi logos?