I have attempted to craft additional cards that are apparently legendary "epic" cards as the game immediately made me recycle them. There should be a feature that doesn't allow you to craft more than two (2) "regular" cards, or more than one (1) legendary. If this isn't possible, at least mark legendary cards as "legendary" to avoid this in the future.
Legendary cards have extra detailing at the bottom. They also have a name rather than creator description and the background round the name text is a different colour.
I agree, until I found this out it was very annoying.
In a future game update, we plan to prevent players from accidentally crafting or purchasing copies of cards beyond the maximum number they can use in decks (2nd copies of legendaries or 3rd copies of other cards).
Please submit a support ticket at https://magicspellslingers-support.wizards.com/hc/en-us/requests/new?ticket_form_id=360000336351 with your account details, and we'll be happy to send you something in the game to make up for that experience.