Assigning users to multiple User Roles

Summary

If a user is assigned to multiple user roles will they have all the rights from all the user roles they are assigned to?

Content

I recently assigned a user to three of our User Roles.  They then came back to me and said they did not have a specific capability that they should have had because it was given to them in one of the User Roles.  

I went and looked at the specific user and the rights they were assigned via a User Roles was not checked off on for the individual user.

I then went and reassigned that user to the specific User Role that had the right they were trying to use. (Did not remove them, just verified they were in the group and readded them)  Then went and looked at the specific user and their rights again, and they now had the rights they needed.