On his photo, Henry Parkhurst Cooke. Captain, 2nd NJ Infantry, and the last CDV is EITHER. I believe he is most likely Edwin Francis, based on the facial resemblance to the one picture of Edwin I was able to find online.... Also he looks older than Frederick's age of 26.
Thoughts / info are welcome. CDVs are about 4" x 2.5" and in very good to excellent antique condition.