Last modified: 2013-02-14 10:54:10 UTC
It is possible for a property to have the same item claimed twice. If you look at this version: https://www.wikidata.org/w/index.php?title=Q57928&oldid=6296393, it has "female" listed twice for sex (will look fine because of bug 44661). Each property should only allow for one copy of an item.
*** This bug has been marked as a duplicate of bug 44763 ***