Yellowjohn, highly unlikely or not, when you go through the process of activation on-line, the MS site actually interrogates the hardware of the PC in question and can tell for instance, if an OEM version of Windows intended for a Dell computer is being installed on a non-Dell PC.
Likewise, attempts to activate multiple installations of a single use licensed copy where the hardware differs from PC to PC will result in rejections by MS.
The serial key is not the only means of identification.