Robert Blake Gets An OJ 2027

this year.

It's true that he became a US citizen, but he's still also a Canadian citizen.

Canadian heritage, as (snip)

That simply means that when a person holds both US citizenship and another citizenship, the US applies it's laws upon the person as if he held US citizenship alone. They ignore the fact that he has another citizenship and will not allow him to deal with the US as anything except a US citizen. At the same time, there is no prohibition to a US citizen holding other citizenships or making use of the rights of the other citizenships when outside the US (as long he doesn't violate US law).

But there is such a thing as dual citizenship, or the simultaneous possession of more than one citizenship.

No. Canadians are only taxed on their worldwide income if they reside in Canada. Canadians who live outside Canada do not have to pay Canadian taxes, or even file Canadian tax returns. That is how most countries implement taxation of income. Taxation is based on residency or on where the income was generated. Very few countries impose tax liability based on citizenship alone, the main ones being the United States and the Philippines. US citizens are subject to US taxation even if they don't live in the US and even if their income is not from US sources.

If he's not a resident of Canada, then that would be true. His citizenship has no bearing on whether he pays Canadian taxes.

Unless he went to a Canadian consulate and formally relinquished Canadian citizenship under Canadian law, that would be false. The fact that he became a US citizen or that the US naturalization oath has a renunciatory statement would have no effect on his Canadian citizenship.