Having US GC will not prevent you from getting Cdn citizenship, of course.
The question will be whether the steps you need to take to maintain US PR status make your claim of number of days spent in Canada trustworthy.
As long as you can prove that you have spent the requisite days in Canada as Cdn PR, you will be granted Cdn citizenship regardless of any other foreign status you may hold at the time.
Whether the time you need to spend in canada wil disqualify you from keeping your GC is another, separate question.
Languishing in Lincoln -No More!!