in this class diagram I would like to represent the fact that, a spec1 can be associated with class2 once a year to a single instance of class2 or several times in the same year to the same class2 or different instances of class2.
Spec2, on the other hand, can be associated with class2 even several times in the same year with class2 with different instances.

I drew these two class diagrams, are they good as a representation of the problem?

for the frequency of associations could I insert a discriminating attribute such as a boolean attribute or an enumeration to indicate if spec1 can have multiple associations in the same year?
If so, what changes when using one or the other?
how would it change in the two class diagrams?