Gaining Nationality

Does anyone know how it is that in most cases players will be able to obtain a nationality after residing in a country for a number of years, but in other cases this is not possible. I play with Olympique de Marseille and most players that I sign will become French after a while. Now I have bought two youngsters from Laos who are not counting down days for obtaining their French nationality. How come? I've seen other cases too...

Is Laos a former French colony?

Wkipedia says: France remained in de facto control until 22 October 1953, when Laos gained full independence

Yes it sure is but how does that answer my question?

Some nations don't allow dual citizenship. I think that's reflected in the game.

That would mean in this case that Laos does not allow its citizens to go abroad and gain a second nationality, really?

They would have to renounce Laotian citizenship.

Then how is it that regens pop up with dual citizenship being French and Lao