她离开了三年了 vs. 她离开三年了 Is there any difference between the two? 她离开了三年了
她离开三年了


My two different textbooks say those two sentences respectively for the one same meaning: "It's been three years since she left." but I'm still not sure because my books are too old and meager in terms of contents. Do they really have the same meaning? If so, can I take the 她离开三年了 as an abbreviated version of 她离开了三年了 which leaves out the aspectual particle 了 after 离开? If there's a difference between the meanings of the two sentences, please let me know.

Thanks for your help in advance!
她离开了三年了: She had been away for 3 years. (She could have been back now or could have not been back.).
她离开三年了: She has been away for 3 years (have not been back). 

她离开了三年了 could be the abbreviated version of 她离开三年了 and is used to describe the same thing, and it could also be different.