Entity Framework. How to map class with nested Enumeration class

Question

I am using an Enumeration class like this

public class SizeUnit : Enumeration {
   public static SizeUnit Inch = new SizeUnit(1, nameof(Inch));
   public static SizeUnit Centimeter = new SizeUnit(2, nameof(Centimeter));

   private SizeUnit(int id, string name) : base(id, name) {}
}

I have another class that references SizeUnit

public class ValueUnit {
   public decimal Value { get; private set; }
   public SizeUnit Unit { get; private set; }
        
   public ValueUnit(decimal value, SizeUnit unit) {
        Value = Decimal.Round(value, 2);
        Unit = unit;
   }
}

I have entity class that references ValueUnit

public sealed class Item : EntityAudit {
   public ValueUnit Height { get; private set; }
   public ValueUnit Weight { get; private set; }

   public Item(ValueUnit height, ValueUnit weight) {
      SetHeight(height);
      SetWeight(weight);
   }

   public void SetHeight(ValueUnit height){
      if (!height.Unit.Equals(SizeUnit.Centimeter) && !height.Unit.Equals(SizeUnit.Inch))
         throw new ArgumentException("Height must be in centimeter or inch");

      Height = height;
   }

   public void SetWeight(ValueUnit weight){
      if (!weight.Unit.Equals(SizeUnit.Kilogram) && !weight.Unit.Equals(SizeUnit.Pound))
         throw new ArgumentException("Weight must be in kilogram or pound");

      Weight = Weight;
   }
}

And I have configuration on DB context

builder.Entity<SizeUnit>().ToTable("VO_SizeUnit").HasData(Enumeration.GetAll<SizeUnit>());

public class ItemEntityTypeConfiguration : IEntityTypeConfiguration<Item> {
   public void Configure(EntityTypeBuilder<Item> builder) {
       builder.ToTable("Items");
            
       builder.OwnsOne(app => app.Height,
           navigationBuilder =>
           {
               navigationBuilder.Property(size => size.Value)
                   .HasColumnName("HeightValue");
               navigationBuilder.HasOne<SizeUnit>(unit => unit.Unit)
                   .WithMany()
                   .HasForeignKey("UnitId");
           });
            
       builder.OwnsOne(app => app.Weight,
           navigationBuilder =>
           {
               navigationBuilder.Property(size => size.Value)
                   .HasColumnName("WeightValue");
               navigationBuilder.HasOne<SizeUnit>(unit => unit.Unit)
                   .WithMany
                  .HasForeignKey("UnitId");
           });
    }
}

After creating a new Item, DB context tries to create a new SizeUnit instead of setting a foreign key to SizeUnit table.

I get an error:

MessageText: duplicate key value violates unique constraint "PK_VO_SizeUnit"

What is the best way to make the HeightUnitId, WeightUnitId fields automatically refer to SizeUnit when creating an Item?

UPD: Enumeration class https://docs.microsoft.com/en-us/dotnet/architecture/microservices/microservice-ddd-cqrs-patterns/enumeration-classes-over-enum-types

public abstract class EntityAudit {
    [Key]
    public Guid Id { get; protected set; }

    public override bool Equals(object obj) {
        var compareTo = obj as Entity;

        if (ReferenceEquals(this, compareTo)) 
           return true;

        if (compareTo is null) return false;
           return Id.Equals(compareTo.Id);
    }

    public static bool operator ==(Entity a, Entity b) {
        if (a is null && b is null) 
           return true;

        if (a is null || b is null) return false;
           return a.Equals(b);
    }

    public static bool operator !=(Entity a, Entity b) {
        return !(a == b);
    }

    public override int GetHashCode() {
        return GetType().GetHashCode() * 907 + Id.GetHashCode();
    }

    public override string ToString() {
        return GetType().Name + " [Id=" + Id + "]";
    }

    public DateTimeOffset CreatedDate { get; set; }
    public DateTimeOffset UpdatedDate { get; set; }
    public DateTimeOffset? DeletedDate { get; set; }

    public Guid? CreatedBy { get; set; }
    public Guid? UpdatedBy { get; set; }
    public Guid? DeletedBy { get; set; }
        
    public bool IsDeleted { get; set; }
}

UPD v2: I solved this problem in this way.

public sealed class Item : EntityAudit {
   [Column("HeightValue")] 
   public decimal HeightValue { get; private set; }
   [Column("HeightUnitId")]
   public int HeightUnitId { get; private set; }

   [Column("WeightValue")] 
   public decimal WeightValue { get; private set; }
   [Column("WeightUnitId")]
   public int WeightUnitId { get; private set; }

   public ValueUnit Height { get; private set; }
   public ValueUnit Weight { get; private set; }
}

public class ItemEntityTypeConfiguration : IEntityTypeConfiguration<Item> {
   public void Configure(EntityTypeBuilder<Item> builder) {
       builder.ToTable("Items");
            
       builder.OwnsOne(app => app.Height,
           navigationBuilder =>
           {
             navigationBuilder.Property(size => size.Value)
                  .HasColumnName("HeightValue");
             navigationBuilder
                  .HasOne(e => e.Unit)
                  .WithMany()
                  .HasForeignKey("HeightUnitId");      
             navigationBuilder
                  .Property("HeightUnitId")
                  .HasColumnName("HeightUnitId");
           });
            
       builder.OwnsOne(app => app.Weight,
           navigationBuilder =>
           {
             navigationBuilder.Property(size => size.Value)
                  .HasColumnName("WeightValue");
             navigationBuilder
                  .HasOne(e => e.Unit)
                  .WithMany()
                  .HasForeignKey("WeightUnitId");      
             navigationBuilder
                  .Property("WeightUnitId")
                  .HasColumnName("WeightUnitId");
           });
    }
}