Is there a single shot shotgun that you can shoot a deer slug and double 00 buckshot?

Slugs and shot are simply the contents of the packaged shotshells. Any shotshell can be filled with shot of various sizes, including 00 buck or with slugs and any shotgun (single shot; pump, double or automatic) that will chamber that shell can shoot those loadings.

One caution is that slugs and buckshot should not be used in shotguns fitted with full chokes. Modified chokes and improved cylinders are probably OK, and full chokes can be used with birdshot (smaller pellets).