Since most vendors source their parts from two or three different places you'll often find that even though you ordered 2000 'identical' computers, they'll have for example two or three different makes of hard drives in them, and sometimes different Bios versions and RAM configurations (2x8GB instead of 4x4GB for example)

If you need 10000 identical severs (ie exactly the same firmware versions, motherboards, hard drive version etc) then that is a bit of a pain since they can't just grab the next 10000 servers out of inventory and ship them to you. You have to make it as a separate special order.