You can import from one catalog by pointing to another. Or, you can open the older / incorrect one and sort your entire catalog by last-edit date and multi-select those 'recent' images and export as a catalog. Then, use just that small-temp catalog as the source import to your main catalog. You'll be closing and opening different catalogs, so don't get confused, such as consider clearly naming / renaming each LRCAT file to assure the purpose of each file, then just double-click to open.

The export as catalog comes from the File menu rather than the Export dialog. The import from another catalog also comes from the File menu. If your two catalogs are about the same size with mostly the same common images, LR runs for a while comparing the images and finally gives you an option for how to import the differences. It's up to you do decide which is the easier process. Export / import or just compare and import.