You can insert a new column E and in E1 put in this formula:

=D1 + D2

assuming these are in Excel date and time formats. Use Format | Cells
to give the cell a Custom format. If this is the only record, then
select E1 and click <copy>, then Edit | Paste Special | Values (check)

If you have more than one record then you can copy the formula in E1
down to cover the records that you have, and then fix the values in
column E as described above. Delete column D, then sort the records so
that the blank rows (except fot the value in column D) will drop to
the bottom, where you can easily delete them.

Hope this helps.

Pete

Probably best to keep separate for future filtering.
This should do it.
If you do NOT want to delete the row with the time then delete the
rows(i).delete line

Sub movecellupandover()
Columns("e").Insert

For i = Cells(Rows.Count, "d").End(xlUp).Row To 2 Step -2
Cells(i, "d").Cut Cells(i - 1, "e")
Rows(i).delete
Next i
End Sub
     A B C D   E F
     1 2 3 1-Jan 10:32 5 6
     1 2 3 2-Jan 11:32 5 6
     1 2 3 3-Jan 12:32 5 6
     1 2 3 4-Jan 13:32 5 6
     1 2 3 5-Jan 14:32 5 6