The two crocodiles arrived in the zoo in 1981. It came from a Dutch animal trader who imported them from Tunisia around 1980.
For 32 years it was believed that they were Nile crocodiles (hence the headline mentioning their "false identity"), but the curator got suspicious when he heard that DNA tests showed that a crocodile in Zurich Zoo was a West African, because that one came from the same animal trader at about the same time. So genetic tests were carried out on the two in Copenhagen, and they turned out to be West African (Crocodylus suchus) too.
In hindsight, this also fits better with their relatively small size and calm temperaments compared to Nile crocodiles.
They have breed a number of times, and according to the article have offspring still alive in other European zoos. The article doesn't say if they are siblings.
Strictly speaking there are four. Two in Copenhagen and two on long-term loan to Dublin, Ireland. All initially believed to be standard Nile. I don't know if there are others of Copenhagen origin (keep in mind that they were in Vincennes, France first), but if there is they're not at the zoo or part of the loan-program.
the Abidjan zoo Cote D' Ivoire insitu/exsitu croc project is for slender snout crocs and not suchus - but they do have around 18 of them - i set the project up 3 years ago