The "problem", if we can call it that, was created by the dual-holder by maintaining the other citizenship. Also, more to the point, this is simply not a problem for the Canadian government to try to solve. It should be between the person, their other citizenship country and the US.

The only time the Canadian government should get involved would be if the person was born elsewhere, renounced other citizenships (ie. only Canadian citizen) and was being given border grief.

Thoughts?