Last year was a pretty notorious year for "copycat" films:

This Is The End and The World's End;

Springbreakers and The Bling Ring (Art films about teenage girls doing bad things);

Olympus Has Fallen and White House Down;

Elysium, After Earth and Oblivion ("Earth is sh*t" sci-fi films);

A Haunted House and Scary Movie 5.

And this year, we got Hercules and The Legend of Hercules. You could also argue that Guardians of the Galaxy and Interstellar are copycat films to a certain extent, because both want to recapture the magic of Star Wars (both Gunn and Nolan have said this in interviews). Besides that though, it's a safe guess that Interstellar will be radically different than Guardians.