The Semantic Web Ontology Language (OWL) is the Semantic Web Version of the Description Logic SHROIQ(D) which has a special Language and Syntax, but its Semantics in the end comes to the Description Logics.
The Web Ontology Language depends or corresponds to a Description Logics. The two different version of OWL, OWL 1 and OWL2 depend on different Description Logics. OWL 1 on SHOIN(D) and OWL 2 on SHROIQ(D)
Also for OWL the Unique Name Assumption does not hold. This means that differences between Entities and Classes must be expressed explicitly. For example Person A may denote the same Person as Person B.
So if two persons or two Instances really are different, then one has to express this in an explicit way.
OWL 2 (SHROIQ(D)) - W3C Recommendation since 2009
OWL Ontology consists of
Open World Assumption
PersonA may also sit next to anohter person... * No Unique Name Assumption - "Difference must be expressed explicitly" + E.g. PersonA possibly denotes the same Individual as PersonB