I'm Canadian I went to Cuba in 2005, and they only stamped my tourist visa card and not my passport. Is there a reason for this? because as you all know there is no embargo for Canada to Cuba.
I don't know this now but in the past, people with different passports from various countries with cuban stamps were either interrogated at US`immigration or were denied visas. I do not know if they are still this strict with cuban stamped passports.
The cuban authorities simple do not stamp any foreign passports if you do not want them to. However they do stamp domincian passports so dominicans have to bribe like 10 dollars - 20 dollars to not have their passport stamped by cuban authorities. I have heard this from dominicans who have traveled to cuba.
AZB