If the destination disk does not have a continuous space to contain the source partition, you can relayout your destination disk by clicking the [Relayout Disk] button when the destination disk item is selected.
If the destination disk is a dynamic, GPT or unrecognized disk, Disk Copy will try to convert the destination disk to an empty, basic disk. Otherwise, Disk Copy will pop a dialog to allow you to delete partitions on the destination disk to make larger continuous space.