Terminology is critical in IT, where similar terms may mean very different things. IMS is a database -- that is, it is software. There is no such thing as an "IMS DB machine". IMS may have multiple instances running on a single z/Architecture machine, but there will be MANY other software products also running on that machine so it is incorrect to merely refer to the box as an IMS machine.
A backup of the IMS data base can be restored to a different physical machine. I believe it can also be restored to another instance on the same machine (but I cannot state that for certainty since I don't use IMS).