Nhibernate added duplicate column on insert - nhibernate

Question

I'm using Fluent NHibernate. I have a class called Audit which has ItemID property. Everytime that I want to save anything in that table give me this error.
Error message:
The column name 'itemid' is specified more than once in the SET clause or column list of an INSERT. A column cannot be assigned more than one value in the same clause. Modify the clause to make sure that a column is updated only once. If this statement updates or inserts columns into a view, column aliasing can conceal the duplication in your code.
Classes
public class Audit : EntityBase
{
/*********
** Accessors
*********/
/// <summary>When the action was logged.</summary>
public virtual DateTime Date { get; set; }
/// <summary>The person who triggered the action.</summary>
public virtual BasicUser User { get; set; }
/// <summary>The name of the related group, used for filtering (e.g. idea, system-settings, site-editor)</summary>
public virtual string ItemGroup { get; set; }
/// <summary>The ID of the related entity.</summary>
public virtual int ItemID { get; set; }
/// <summary>The title of the related entity.</summary>
public virtual LocalizableString ItemTitle { get; set; }
/*********
** Public methods
*********/
/// <summary>Construct an instance.</summary>
public Audit() { }
}
Mapping:
public class AuditMapper<T> : IEntityMapper<T>
where T : Audit
{
public virtual void ExtendDomainModel(IEntityMetadata<T> metadata)
{
metadata.MapTablePerClassHierarchy<Audit, T>("`ItemGroup`");
if (!metadata.IsSubclass)
{
metadata.Map.ManyToOne(entity => entity.User, relation => relation.Column("`userid`"));
metadata.Map.Property(c => c.ItemGroup, mapper =>
{
mapper.Insert(false);
mapper.Update(false);
});
metadata.Map.Property(c => c.ItemID, mapper => mapper.Column("itemid"));
}
else
{
metadata.MapSubclass.ManyToOne(entity => entity.User, relation => relation.Column("`userid`"));
metadata.MapSubclass.Property(c => c.ItemGroup, mapper =>
{
mapper.Insert(false);
mapper.Update(false);
});
metadata.MapSubclass.Property(c => c.ItemID, mapper =>
{
mapper.Insert(false);
mapper.Update(false);
});
}
}
}
SQL Query:
INSERT INTO [brainbank].[idealink.core.audit] ([date], [userid], itemid, [itemtitle_key], [itemtitle_original], [itemid], [ItemGroup]) VALUES (#p0, #p1, #p2, #p3, #p4, #p5, 'IdeaAudit'); select SCOPE_IDENTITY()

Answer 1

I fix this issue in my mapper.
I changed
metadata.Map.Property(c => c.ItemID, mapper => mapper.Column("itemid"));
to
metadata.Map.Property(c => c.ItemID, mapper =>
{
mapper.Insert(false);
mapper.Update(false);
});