In the attached cell AM1 contains your start date (which you can adjust).
Cell A3 contains a formula which uses AM1 to create the first date.
Then in cell A20 there is:
Code:
=IF(COUNTIF($A$3:$A19,$A3)>1,"Date: " & TEXT(DATE(RIGHT($A3,4),MID($A3,10,2),MID($A3,7,2))+1,"dd/mm/yyy"),$A3)
This can be copied to every 17th row as has been done in the attached.