They have in the past - I believe the young were 'returned' to Africa, as everywhere else in Europe has michaeli and any young from this pair would obviously be related to each other. Rather odd situation, but interesting things to see.
And they did both have quite distinctive horns - not sure if this is a feature of minor or if these are just particularly exceptional individuals.
A little bit sad, that they send the baby rhinos back to africa. Was there no zoo interested in them ? I think, it was not a good idea to release them into the wild because that means a very high risks for their life.