I found some newly posted questions with duplicate titles. Is this a bug?

I just saw at least two new posts with a title that matches two existing canonical duplicates:

• What is a NullPointerException, and how do I fix it? (duplicating What is a NullPointerException, and how do I fix it?)
• https://stackoverflow.com/questions/74788833/what-causes-a-java-lang-arrayindexoutofboundsexception-and-how-do-i-prevent-it (duplicating What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?)

As far as I'm aware, posting duplicate titles should not be possible and should produce an error that the title already exists. How was it possible that these two new questions were posted?

^{The fact they match the canonical exactly demonstrates why this was not allowed in the first place}