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!