.NET (Core and Framework)

<pre>I create winforms app, and have tabcontroll with some tabpage.In one of then tabpage I have grid.Grid must be have checkbox on the collumns.When I load forms and click on tabpage grid render ok,but when I load forms and select tabpage force grid duplicate collumns,and not checked checkbox?
Its part for render grid, Methode UcitajKontakta.

<pre lang="c#">dbgPacijentKontakt.DataSource = _t;



            if (dbgPacijentKontakt.RowCount > 0)
            {
                for (var i = 0; i < dbgPacijentKontakt.Columns.Count; i++)
                {
                    DataGridViewColumn column = dbgPacijentKontakt.Columns[i];
                    if (!new[] { "Email rezultati", "Email lab", "Sms podsetnik" }.Contains(column.HeaderText))
                    {
                        continue;
                    }
                    DataGridViewCheckBoxColumn column1 = new DataGridViewCheckBoxColumn();
                    column1.HeaderText = column.HeaderText;
                    column1.Name = column.Name;
                    column1.CellTemplate = new DataGridViewCheckBoxCell();

                    dbgPacijentKontakt.Columns.Remove(column);
                    dbgPacijentKontakt.Columns.Insert(i, column1);


                }
                dbgPacijentKontakt.CommitEdit(DataGridViewDataErrorContexts.Commit);
                for (int i = 0; i < _t.Rows.Count; i++)
                {
                    dbgPacijentKontakt["Sms_podsetnik", i].Value = bool.Parse(_t.Rows[i]["Sms_podsetnik"].ToString());
                  



                }     

IEnumerable

IDisposable