By default you cannot do it multiple times.
A retake is on special request. Contact firstname.lastname@example.org for a retake.
When taking the online Rapid Developer Path, the knowledge checks do prepare you for the Rapid Developer Certification Exam. Passing them with 80% or higher is a good indication of having the right level of understanding.
Small advise; don't prepare for a retake.
You can do it multiple times and no the questions will not be the same :)
I am not sure about the questions. It took my only one time to pass.
But yes, you can do it multiple times.