回复：回复：只有中国不承认双重国籍，对于美国而言，你是加拿大中国

My personal opinion it may never be a problem if you do not tell them unless they ask about it, although you should have at least notified them during the interview time. There are quite a few discussions regarding how to make sure naturalized citizens abandon their former nationality at oath but never reached any concrete results even at legislation -- for example, some EU countries put in their constitution that citizens can not choose to abandon their citizenship.

When you apply for citizenship later, it is probably a good place to sort this out clearly.