Douglas,
I take it you have the same images on both computers? Are they all RAW files?
If they're all RAW files, you could copy the XMP sidecar files to the other system. But if you have other file types or some of your RAW files have IPTC/XMP embedded in them, you'd have to copy the images themselves to the other system.
If you really need to work with the images on both computers, you'd be better off using a file server and work with the files on the server. Otherwise there are other solutions like rsync-based utilities that can synchronize folders on two or more filesystems. Here is an example of one that provides a nice user interface for rsync and is free:
https://www.macupdate.com/app/mac/20983/arrsyncHTH,
-Kirk