Originally Posted by
hfly
In any case to answer to OP, most citizenship laws exist in a vacuum, so theoretically there is no limit on what can hold as long as one is not from a country which categorically prohibits duel or multiple citizenship (places such as Malaysia, China, India, Austria (with very few caveats), and certain others which come to mind.
Actually, even if you hail from a country which prohibits dual/multiple citizenship, does not mean there aren't people who successfully do so. Singapore is one such country, and I personally know quite a few people in SG who have dual/multiple citizenship. It's pretty much an open secret.
Ultimately, the bestowing of citizenship is a sovereign right. If the Canadian govt wishes to grant citizenship to a Singaporean - the SG govt cannot forbid it, they can only revoke the SG citizenship. But if the SG govt doesn't know, what would they do?
And for a foreigner taking up SG citizenship, the SG govt will ask for a certificate proving you have renounced your original citizenship - but for some countries, it is also very easy to then recover that citizenship. So a newly minted SG citizen just heads back to the home country and gets the paperwork done. Only countries with a very close political relationship may ask for proof that the SG citizenship has been renounced, but even then - knowing the right people or accessing the right channels is all it takes.