Consider the following:
If I don’t go to the movies because of your nagging …
It conveys two possible meanings:
If your nagging causes me not to go to the movies …
If I go to the movies for one or more reasons other than your nagging …
I encounter this sporadically in my general writing, but I don’t recall having seen it in contracts. Have you?
Also, have you encountered any discussion of this ambiguity? Have I characterized it correctly?