Reports and scripts : a beginner questions

I don't have any experience with versioning reports, can't help you there.

Regarding your second question:

Your approach doesn't work in 100 % of all imaginable test cases.

Plug two occurrences with the same object definition into the same model, and let a report check whether or not they are the same occurrence with your approach. Your report would tell you they are the same, even though they are not the same (they only share the same object definition, but can be placed in different parts of your model graph).

You can either scratch the .ObjDef() from your way of doing it (occurrences have an ObjectID() method too), or use the more convenient wrapper method .IsEqual(...) which you can find for many object types (occurrences, object definitions, databases,...). .IsEqual(...) compares objects using their ObjectIDs too, but it's easier to use.

  if (relations_list[i].TargetObjOcc().IsEqual(anObjOcc))

.IsEqual(...) simply returns the boolean true if the ObjectIDs match, or false if they don't match.

Thanks Key

If I understand well :

relations_list[i].TargetObjOcc().IsEqual(anObjOcc) is True when TargetObjOcc and anObjOcc are the same occurrences

while 

relations_list[i].TargetObjOcc().ObjDef().IsEqual(anObjOcc.Def()) is True when TargetObjOcc and anObjOcc relate to the same Object definition (but are possibly different occurrences , maybe in the same model)

That's correct.