public class TableA
{
   public int Id {get;set;}

   public int TableBRefAId {get; set;}

   public int TableBRefBId {get; set;}

   [Required]
   public TableB ItemA {get;set;}

   [Required]
   public TableB ItemB {get;set;}
}

public class TableB
{
    public int Id {get;set;}

    public virtual IList<TableA> TableAList { get; set; }
}

protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<TableA>()
            .HasRequired<TableB>(p => p.ItemA)
            .WithMany(pp => pp.TableAList )
            //.HasForeignKey(x => x.TableBRefAId)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<TableA>()
            .HasRequired<TableB>(p => p.ItemB)
            .WithMany(pp => pp.TableAList )
            //.HasForeignKey(x => x.TableBRefBId)
            .WillCascadeOnDelete(false);
    }