Usually and almost always happening is that if you move files using drag and drop from any folders on one drive to any folders on a different drive, for example from the hard drive on the computer to a USB memory stick, from hard drive on computer to an external drive, from USB to hard drive, from one external drive to another external drive, from memory card in a camera to computer, any drives to any other drives, they tend to leave the original on the current drive, and make copies to the target drive. Unless you change the settings in Control Panel or any other settings.
When it is moving from one folder to another folder on the same drive, it always move not copy.