You may see "Dummy" entries in the DLC menu after installation. These are placeholders and can generally be ignored or deleted safely.
You can find the undub files for the base game, updates, and DLC on : fire emblem echoes shadows of valentia undub link
The most reliable source for a pre-patched version of the game is the hShop , which hosts a dedicated entry. You may see "Dummy" entries in the DLC