What is the criteria set in the plugin for duplicate questions?

I have installed the latest version of this plugin and I have noticed at times when writing questions I get a redirection to a page with a message

"It seems that this question was already asked. Click here to view it, if it is approved by the admin. If title or content of your question is the same as any of the previous questions, it is regarded as duplicate."

Now, maybe in some cases I might have written "test question" (as I am testing functionality) but not all the time and I have seen this message quite a few times.

Can you let me know what criteria the plugin looks for to spawn this message? Is it checking to see if the title of the question exists already in the DB to the exact characters?

I could not see any info in the documentation

Thanks