dropdownlist items doubling up

I have a number of dropdownlists that are bound to the same gridview datasource.
I need to have a blank row at the top of each.
So my dropdownlist settings look like this. (Each list is identical except for the ID):

            EnableViewState = "True"
            <asp:ListItem Value=""></asp:ListItem>

This works perfectly for me except on postback the dropdownlist doubles up with entries. If I take out the AppendDataBoundItems the problem is fixed but I then do not get a blank row. If I clear the items in my sub I lose my selected item. Can someone please let me know how I can have a dropdownlist that allows me a blank row at the top, retains its selection on postback and does not double up its items on postback
thx heaps
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Jeff CertainCommented:
In your page load

If not Me.IsPostback Then
' load combo box here
End If
verdanteAuthor Commented:
Thx Chaosian
In this scenario do I programatically assign the datasource to each dropdwonlist as opposed to specifying a static datasourceid in each dropdownlist definition?
Jeff CertainCommented:
I usually retrieve the data, then operate programatically on the DataTable to insert the new row.

' Get the data and put it into the DataTable dt
Dim row as DataRow = dt.NewRow
dt("ID_column_name") = 0
dt("description_column_name") = string.empty
dt.rows.insertat(row, 0)

Of course, I generally don't use the drag-and-drop data sources -- partly beacuse of limitations like this one.

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verdanteAuthor Commented:
Thank you very much for your response. It's enormously helpful for those with limited experience like me to gain such valuable advice.
Jeff CertainCommented:
My pleasure -- always glad to help.  We were all there once....
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