Ciao Daniele,
I think the rule is there to forbid an infinite number of bonds resolving in a single session, since it's the players who decide if the bonds warrant a resolution.
Not so much as "you may become too powerful!", but rather "What's your story about?". It helps to give every bond some importance.
But, if you have two bonds instead of one, and you played them, I see nothing wrong with resolving both. Or is it better to follow the rules at all costs? Boh...