Steven,
If you add the swatches to the CC Library, it should be available to the second installation of Illustrator on the iMac. It should also be available to InDesign, Photoshop and other CC applications. If the iMac installation is associated with a different account, then you might need to save the swatches and manually copy that .ai or .ase file to the iMac. Choose Load Swatches from the Swatches Panel menu, navigate to the file you copied over to access those swatches.