Many have two graphics processors, yes.
The default one (Intel HD) is part of the CPU package (APU), and is automatically used by Windows and any app/game which hasn't been configured to use the more powerful AMD/Nvidia GPU. These laptops are able switch from one GPU to the other automatically.
Since the Intel GPU is the default for Windows and apps, that's why your friends laptop still works even though the high-performance GPU is (or seems to be) dead.