Am 08.07.2015 um 09:45 schrieb Gerard Meijssen:
Hoi, Given that we only support 280+ languages, I am fairly certain that this restriction will bite us. I strongly urge you to allow for it but monitor for it and see what can be done.
Property labels are unique per language, not globally. They always have been. Properties can be accessed by their name (label) in wikitext, so they have to be unique.
We now want to make it possibel to also access properties by their alias (otherwise, changing a property label will break all pages that have been using it). This requires property aliases to also be unique per language.