Why not?
You can write about different things and end up to have a same title you think best describe your book.
There's plenty of them.
For example, this is a recent read of mine,
https://www.goodreads.com/book/show/49750133-finding-identity
It is a poetry book named Finding Identity.
It talks about the author's search for who he/she is, with different poems and proses that expose to different topics and other areas of life, and each of them approaches to the inner self
This is another book named Finding Identity
https://www.goodreads.com/book/show/14306166-finding-identity
It is a book of short stories about the struggle of human existence and how an adult try to fit in to the society
A single-word title for books would be even more common. Like the word "confession". Here is a whole list of them, the stories are all different:
https://www.goodreads.com/search?utf8=%E2%9C%93&q=confession&search_type=books