The 360 went through a few development kits, all with different specs really. Alpha kits were Power PC Apple computers, then beta 1 and 2 at least with different specs, some not accepting wireless controllers correctly, and plenty of other tests inbetween. Plus, multiple versions! And prototypes of the new revisions of motherboards, prototypes of the Slims, XDA kits, the list goes on really.
Of course, the Xbox 1 had Alpha 1 and Alpha 2 PC towers, the beta DVT3 kit, a slightly later DVT3 with a more final green jewel (no longer metal), and DVT4s, plus debug kits and prototypes inbetween.
Even the Wii had a few. Dreamcast had multiple kits, ranging from things like the Set 2 which were installed into PCs, to Katana kits, to later Dreamcast kits, with various versions of course.
So yeah, probably not unusual, depending on what is actually changing
I wish there was a picture of that somewhere.
There are pictures of it, at least part of it. The rumored prototype 3ds kit that some sites leaked, which were big motherboards, are those kits. They didn't even ship with the right amount of cameras installed, and were often added on as Nintendo sent them.
