回复：只有中国不承认双重国籍，对于美国而言，你是加拿大中国双重身

I am at the same boat as you. I didn't notify USCIS the changes of Citizenship. and later I got my GC.On GC it only said country of birth is China.
But I havn't used my Canada passport together with GC crossing border. I am not sure if I will be questioned about this.