multiple association classes on the same relation

I want to add multiple association classes on the same relation, to manage absence and group affection between a student and course, I read that an association class is a description of a relation, so to not be in conflict with this definition I draw 2 relations between my classes, and for each relation there is a corresponding association class.

here is my current UML diagram:

the diagram with multiple association classes on the same relation:

so which on is following UML standards.

both diagram I believe will be translated into the same relation database scheme, so I just don't know which one is actually following the UML standards.

The association class in UML is at the same time an association and a class. The consequence is that it is the same thing with a unique name:

• The first diagram is correct: two different association classes between the same classes are legit, and correspond to two different semantic relationships (absences and belongingness are two different concerns).

• The second diagram is not valid UML, since the two association classes cannot and do not share the same name.