Column names in each table must be unique. Column name ‘LastName’ in table ‘HumanCustomers’ is specified more than once

After update my model and add data annotation.

then use add-migration and update-database command get below error:

Column names in each table must be unique. Column name ‘LastName’ in table ‘HumanCustomers’ is specified more than once.

But LastName field once used.

for guid:

HumanCustomer Class:

public class HumanCustomer     {         public int Id { get; set; }         public int UserId { get; set; }         [Required]         [MinLength(2)]         [MaxLength(20)]         public string Name         {             get => Name;             set             {                 value.TrimAndReduce();             }         }         [Required]         [MinLength(2)]         [MaxLength(20)]         public string LastName         {             get => LastName;             set             {                 value = value.TrimAndReduce();             }         }         [NotMapped]         public string FullName         {             get { return Name + LastName; }          }         [Required(AllowEmptyStrings = true)]         public int GenderId { get; set; }         public string Address { get; set; }         public string Phone { get; set; }         [DataType(DataType.EmailAddress)]         [EmailAddress]         public string Email { get; set; }         public DateTime BirthDate { get; set; }         public int IdentityTypeId { get; set; }         public string IdentityCode { get; set; }            [Required]         [ForeignKey("UserId")]         public virtual User User { get; set; }           [Required]         [ForeignKey("IdentityTypeId")]         public virtual IdentityType IdentityType { get; set; }         [Required]         [ForeignKey("GenderId")]         public virtual Gender Gender { get; set; }     } 

and migration:

 protected override void Up(MigrationBuilder migrationBuilder)         {             migrationBuilder.AddColumn<string>(                 name: "LastName",                 table: "HumanCustomers",                 maxLength: 20,                 nullable: false,                 defaultValue: "");              migrationBuilder.AddColumn<string>(                 name: "Name",                 table: "HumanCustomers",                 maxLength: 20,                 nullable: false,                 defaultValue: "");         }          protected override void Down(MigrationBuilder migrationBuilder)         {             migrationBuilder.DropColumn(                 name: "LastName",                 table: "HumanCustomers");              migrationBuilder.DropColumn(                 name: "Name",                 table: "HumanCustomers");         }