Relation of Users & Duplicates

So does Backendless automatically prevent the addition of duplicate objects when adding relations? For example, if you have a relation to many Users: it will prevent duplicates of users from getting added to the relation?
As I test this, it seems to be the case that you automatically handle this. The reason I ask is because I was anticipating having to prevent this myself but am noticing I might not have to.
Also going a bit off of the answer from this question where it’s said:

When you update an object, make sure to include it's objectId property. If the property is not present, Backendless will create a new object.

Backendless will take care of it - the same object cannot be become twice–related to another object.