'Napoleon Dynamite' Star -- Twin Brother Lashes Out ... MOVIE RUINED

Fun Fact: Did you know "Pedro" from the 2004 hit "Napoleon Dynamite" has a twin brother?

Not So Fun Fact: "Pedro" threatened to sue his twin brother for more than $10 MILLION for impersonating him without permission ... and now the bros don't speak.

It all came to a head in 2008, when Efren Ramirez (the real Pedro) sent a cease-and-desist letter to his brother Carlos Ramirez ... warning him to stop making public appearances as "Efren."

We spoke to Carlos ... who tells us he only started impersonating Efren at his brother's request, when Efren was "too busy" to make the appearances himself.

But Carlos admits he took things too far ... saying, "I did attend an event without his knowledge as I was being immature and wanted to get back at him for a personal matter which involved the girl I was dating at the time."

Carlos says the rift between the two got so bad, Efren's lawyer fired off a letter instructing Carlos to stop "interfering with [Efren's] personal and professional life" ... or else Efren would sue his brother for more than $10 million.

Carlos says he got the message loud and clear ... and started focusing on his own acting career.

Now Carlos is determined to put the past behind him and wants to salvage his relationship with his bro ... telling TMZ, "I would love to talk to Efren. Maybe even work together in the future. His support would be amazing."

He also says, "I think it's safe to say the magnitude of 'Napoleon Dynamite' and everything that has come along with it, has ruined my relationship with my twin."

As for Efren ... we reached out to his rep for comment who told us, "Efren prefers to keep what's between he and Carlos, between he and Carlos."