When the MBR is selected along with the disk backup, you need to retain operating system bootability on the target disk volume. The operating system must have the system volume information (e.g. volume letter) matched with the disk NT signature, which is kept in the MBR disk record. But two disks with the same NT signature cannot work properly under one operating system.
If there are two disks having the same NT signature and comprising of a system volume on a machine, at the startup the operating system runs from the first disk, discovers the same signature on the second one, automatically generates a new unique NT signature and assigns it to the second disk. As a result, all the volumes on the second disk will lose their letters, all paths will be invalid on the disk, and programs won’t find their files. The operating system on that disk will be unbootable.
To retain system bootability on the target disk volume, choose one of the following: