Using a backup for time machine

I have to get my Macbook pro sent in for repairs. Creating a back up to load into a used iMac someone gave me. Can I use it for the iMac and to restore my Macbook pro when it comes back to me.? Just now sure if when I do a restore from timeline if it takes the data out of my external harddrive or is just making copies of it and it stays on my external WD hardrive.