Double entry in database

UserBLL
public class UserBLL
{
	public UserBLL()
	{
		
	}
    public Int32 saveUserDetails(clsUser objUser)
    {
        UserDAO objADO = new UserDAO();
        return objADO.saveUserDetails(objUser);
    }
}

UserDAO
    public int saveUserDetails(clsUser objUser)
    {
        SqlCommand objCmd = new SqlCommand("usp_InsertNewUser");
        object result;
        try
        {
            objCmd.Connection = objCon;
            objCmd.CommandType = CommandType.StoredProcedure;
            objCmd.Parameters.AddWithValue("@username", objUser.username.ToString());
            objCmd.Parameters.AddWithValue("@pwd", objUser.pwd.ToString());
            objCmd.Parameters.AddWithValue("@fname", objUser.firstname.ToString());
            objCmd.Parameters.AddWithValue("@lname", objUser.lastname.ToString());
            objCmd.Parameters.AddWithValue("@contact", objUser.contact.ToString());
            
            if (objCon.State == ConnectionState.Closed)
            {
                objCon.Open();
            }
            result = objCmd.ExecuteScalar();
        }
        catch (Exception ex)
        {
            return -1;
        }
        finally
        {
            objCmd.Dispose();
        }
        return Convert.ToInt32(result);
    }

return objADO.saveUserDetails(objUser);