Not that I know of, but you can click the "New" button (near "Done") and create a second AFNI window. If in this new window you choose an underlay in the same space as the original (possibly the same image), the two windows will be locked together and clicking around in one window will move the crosshairs in both. This way you can look at two overlays over the same underlay, even if the two overlays don't layer in one window.

Isaac