The first question underestimates the number of multiple answers—the fact that people can speak two languages. That's fairly clear.
I don't think I have talked about that in my presentation. I probably skipped it. I have all the statistics on that with me. When Statistics Canada asks for multiple answers, it is talking about Canada in general. The figure is 1.9%, which seems to indicate that the problem is insignificant. Even when the question does not encourage indicating that two languages are spoken, 10.6% of francophones in exogamous situations say that they speak two languages. That number goes up to 19% in British Columbia.
Multiple answers exist, and there would be even more of them if the question encouraged people more to show, for instance, that we are not forced to use the second language equally often as the majority language in order to speak two mother tongues. Socio-linguistically speaking, there is no defence for that.