USERELATIONSHIP impact on other relationships

Hi, I'm trying to understand how USERELATIONSHIP() works and went into question how does it decide which undefined active relationship to use when there is more than one to the same table.

In my example both tables 'users' and 'usage' have active relationships to the table 'calendar' and one inactive 1 to 1 relationship between them. I have two measures created:

Measure_usage = calculate(sum(usage[usage]), userelationship(usage[user_id], users[user_id]))

Measure_users = calculate(count(users[user_id]), userelationship(usage[user_id], users[user_id]))

Then I create two table visuals with calendar[date] field and those measures to test which calendar relationship will it use - results are that both measures use relationship users[created_at]<->calendar[date].

Could anyone explain why is it so?