(From row In Dt.AsEnumerable()
Group row By index = Dt.Rows.IndexOf(row) \ 2 Into Group
Select Dt1.Clone().Rows.Add(Group.SelectMany(Function(r) r.ItemArray).ToArray())
).CopyToDataTable()
Maybe also an Alternate with Skip and Take methods like below :
OutputDT = (From i In Enumerable.Range(0,CInt(Math.Ceiling(DT.Rows.Count/2)))
Let arr = DT.AsEnumerable.Skip(CInt(i*2)).Take(2).Select(Function(y)y(0).ToString).ToArray
Select OutputDT.Rows.Add(arr)).CopyToDatatable
Here, DT is the input datatable with the First Column containing values and OutputDT is a datatable which is prepared as needed for the Output Representation (Two Columns) using Build Datatable Activity.