var result = JensKakhat.GroupBy(g => g.Id)
.Select(g => g.First())
.ToList();
PnlTypePaper.Visible = result.Any();
DdlTypePaper.DataSource = result;
DdlTypePaper.DataTextField = "ItemNine";
DdlTypePaper.DataValueField = "Id";
DdlTypePaper.DataBind();