NonUniqueObjectException was caught NHibernate C#

Question

NonUniqueObjectException was caught 

'a different object with the same identifier value was already associated with the session: 64, of entity' at SaveOrUpdate method NHibernate Exception C#

Savint Two Objects in Single Method Using SaveOrUpdate() method Showing the above exception

my code is as below
i.e.,

object1=SaveOrUpdate(object1)

forearch(var item in object2)
{
otherObjectRepository.SaveOrUpdate(item);
}


please hlep me to rectify the error..