It's a confusing explanation and I'm not sure what has happened.
However, the best way to get work from a laptop to your main machine is not to save the XMP and copy files across using Finder. Instead, in Lightroom on the laptop, select the images and choose File > Export as Catalog. Assuming you have disc space, select Include Negatives. And always tick Include Previews. Point this to a folder on your desktop, and let Lightroom finish the export job. Get this folder onto your main computer's desktop, open your main Lightroom catalogue, and use File > Import from Catalog to point to the exported data. Job done.
John