The answer is probably No but I'll ask anyways.
There are plans that have 500 local minutes and 1000 international minutes. If I were to run out of local minutes would the international minutes be used in place?
My answer would be the same as yours. I think the purpose of putting 2 categories is to distinguish one from the other. If not it would've been easier to put 1500 local & international minutes in one sentence.
Nitty Gritty from the site: 1000 bonus international long distance minutes apply to calls made to India, Germany, China, Hong Kong, Bangladesh, United Kingdom, Italy, Mexico, Australia & Taiwan.The minutes you use while travelling outside Canada are charged separately. The airtime required to connect your calls is drawn from your included plan minutes
It means you can make 1000 minutes call to those countries without international long distance charges. It still use your included anytime minutes if you made calls during day time(outside of your unlimited minutes window)