2 times data is inserting(duplication) 3 tier architecture

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C#

ASP.NET

DATA layer code method

public int AddUsers(Users objUser)
       {
           SqlConnection con = new SqlConnection(ConnString);
           con.Open();
           SqlCommand cmd = new SqlCommand("SpCreateUser", con);
           cmd.CommandType = CommandType.StoredProcedure;
           try
           {
               cmd.Parameters.AddWithValue("@Full_name", objUser.fullname);
               cmd.Parameters.AddWithValue("@Dob", objUser.DOB);
               cmd.Parameters.AddWithValue("@email", objUser.Email);
               cmd.Parameters.AddWithValue("@phoneno", objUser.Phoneno);
               cmd.Parameters.AddWithValue("@loginid", objUser.loginId);
               cmd.Parameters.AddWithValue("@pwd", objUser.Password);
               cmd.ExecuteNonQuery();

               int totalrecordscreated = (int)cmd.ExecuteNonQuery();
               return totalrecordscreated;
           }
           catch (Exception ex)
           {
               throw ex;
           }
           finally
           {
               con.Close();
           }
       }

Business layer Method :

public int AddUsers(Users objUser)
        {
            DataLayer objUserDAL = new DataLayer();
            try
            {              
                return objUserDAL.AddUsers(objUser);
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                //objUser = null;
            }
        }

UI layer- register.aspx.cs

protected void btnRegsubmit_Click(object sender, EventArgs e)
{
   Users objUser = new Users();
   objUser.fullname = tbfullname.Text;
   objUser.DOB = tbdob.Text;
   objUser.Email = tbemail.Text;
   objUser.Phoneno = tbphoneno.Text;
   objUser.loginId = tbloginid.Text;
   objUser.Password = tbpwd.Text;

   BAL objBAL = new BAL();

   int records_no = objBAL.AddUsers(objUser);
   Response.Write("No of created records " + records_no.ToString());

}

data:

Trans_id	Date	Person_id	Payee_details	Amount	Expense_Type
20	2018-08-27	admin	food panda	254	Food
21	2018-08-27	admin	VRl	600	Travel
22	2018-08-14	sam	rewgrg	564	Food
23	2018-08-14	sam	rewgrg	564	Food

having interfaces for DAL and BLL layers. after submitting the data records are inserting two times(duplication.) What logic is wrong here?

What I have tried:

Help me since i am new to coding, not understanding what logic is creating this problem