When you place a native Photoshop file (PSD) or TIFF file in InDesign, any spot-color channels the file contains appear in the Swatches panel as spot-color inks. You can select and apply these swatches to other objects in your document; to delete these swatches, however, you must first delete the placed image.

If you import a file that has a spot-color channel with the same name as a spot color in your document, but with different color values, you will be asked whether you want to use the color values in the placed file or the ones in the document.