I'm writing a romance novel and want to include some scenes that are described first from the female protagonist point of view and then from the male. Will readers think it's a waste of time (as the same events are described twice) or is it a legitimate thing to do?
A varying viewpoint can be a useful component of the story, but only if there is some plot advancement. (See TVTrope's Rashomon Style entry for various examples.)
Unless the differences from the two character's perspectives are of pivotal importance to the story, don't do it.
OK, this example is not a novel, nor even great art, but bear with me. I'm thinking of the opening of "Grease." First you have the true summer romance of Danny and Sandy. Then later you have the interwoven telling of the summer romance, by Danny to his guy friends, and by Sandy to her new girl friends. Danny's account exaggerates the physical, while Sandy's account exaggerates the spiritual/emotional.
Given that this movie was a success, and this was a great opening to the movie (setting up much of the plot), I conclude that what you are proposing CAN be done successfully. However, I think it's going to be REALLY hard to do it successfully in a novel.
My suggestion is to use third person narrative, but then have your two romantic protagonists tell their version of the events (in first person narrative, of course) to someone else. That "someone else" could be the same person(s) or different person(s). In this manner, you add plot elements in the twice-telling of one event.
Why not? The most famous example is probably from film: Akira Kurosawa's Rashomon.
Another example that immediately comes to mind in the romance context is a short story I once read (but don't remember the author or title) where a couple, who are happy in love, remember how they met each other and got together, but in the retelling they realize that they have completely different and contradictory memories, which gives the impression that the person they are talking to (in the present) could not possibly be their partner at all. In this case, the memory is told in alternating direct speech, with the beginning of the memory being identical, but then more and more differences appear, until they are no longer compatible.
Other popular examples are crime stories that are often told from the perspective of the criminal and the sleuth. A love story is not that different from a crime story. In love, too, we have two "opposing" protagonists who experience different aspects of the same events. And their misunderstandings, differing aims and ideals, and so on, are what makes love exciting (and a bit frightening) in real life. So a story that tells falling in love as the "crime" plot it is, elaborating how two different people finally arrive at the same goal despite their contradictory expectations, can increase the value of the story, if it is handled well.
I've seen this twice. Once in Haruki Murakami's 1Q84 and Natsuo Kirino's Out. The reaction of the readers was: "Hey, you already told me that!" My reaction was: "Damn, you already told me that."
I have seen this done well. John Scalsi Did it in Zoé's Tail where he retold events from an earlier novel from another perspective (the earlier book was told from the father's point of view this one from the daughter's). He did it well. He also said it was vary difficult.
I think this is a legit way to write romance, and Judith McNaught uses it in her stories, particularly A Kingdom of Dreams. She artfully mixes POV's of Jenny (the heroine) and Royce (the hero) in a single scene where they're both present, but without repetition. One character begins the scene, the other ends it, for example. I think it's very useful to describe sexual encounters if you have any.
However, this is a difficult technique, so you may want to read this article by K.M. Weiland, especially to avoid head-hopping:
when the narrative breaks “out of POV” and jumps without warning from the perspective of one character into the perspective of another.
Gone Girl does this to a certain extent but it does make an effort to forward the plot with the separate view points. Long as you're doing something with it, I don't see why not.
Honestly, If you are going to describe the same events from 2 POVs I won't really like it unless you use one POV to start the event and things start to escalade and advance form the other POV. Like instead of talking about the same event you can sort of advance the events. A perfect example would be a recent book I read by Veronica Roth (Allegiant). Although it seemed kind of weird when I heard she was going to write it that way, it actually turned out great and every POV was different and contributed to the twist in the story.