This absolutely does happen all the time.
Saying it is the same is like saying every love story where there is family conflict is the retelling of Romeo and Juliet. As said of West Side Story.
Yet, they are very different in their presentation.
Oh Brother Where Art Thou, the Odyssey.
The Lion the Witch and The Wardrobe, the biblical New Testament.
Every search for a soulmate, Plato’s symposium.
Every Hero’s Journey, Classic Mythology.
You get the point.
Therefore, I present this idea for you to consider.
If people falling in love is the same, and detectives pursuing criminals is the same, their crime solving methods identical, or a difficult family life, coming of age, being torn apart by guilt, loss, inner conflict, or achieving joy, success and happiness after a hard won struggle are all considered the same, well then ok, all stories are the same.
( but only in the way that the human experience displays struggles and choices to cause and effect situations with believable responses to those situations. Does it not? Even the insane must demonstrate believable human behavior.)
I have heard this advice to your very question and I agree with it.
“It doesn’t matter if the story has been told before, because it wasn’t told by you!”
Your voice is unique and you will create a fresh expression of it, because you are a different storyteller.
For myself I would not choose to read their book if you feel any similarities could drain the wind from your sails.
I would write the story as planned with faith that it will be chalked full of mostly differences. (as I remind myself, in my genre that just because I have read one psychological thriller doesn’t mean I don’t want to read them ALL of the psychological thrillers, because I DO! )
Isn’t that what a genre is about? People who are fans of a specific story being told by as many different story tellers as possible?
So write that novel, your way and fooie on anyone that discourages your rendition being told.
I can hardly wait to see your signature style of graceful and elegant words adorning any story you chose to tell.
I am already a fan!
Write On!