Hi again,
apologies, my intention was to reply to my original post:
https://lists.gnu.org/archive/html/emacs-orgmode/2016-10/msg00148.html

When archiving to datetree:
(setq org-archive-location "file.ext::datetree/")

ECM:

* Minimal Example
** DONE 1: One Empty Line After
   CLOSED: [2016-06-28 Tue 21:00]

** DONE 2: Two Empty Lines After
   CLOSED: [2016-06-14 Tue 21:00]


** DONE 3: Extra


The following produces unexpected result on "Minimal Example":
1. Archive first TODO "1".

2. Archive second TODO "2".


Result (three (3 = 2 +1) empty lines between the tasks, the properties have
been deleted for readability):
* 2016
** 2016-06 June
*** 2016-06-14 Tuesday
**** DONE 2: Two Empty Lines After
     CLOSED: [2016-06-14 Tue 21:00]
     :PROPERTIES:
     :END:



*** 2016-06-28 Tuesday
**** DONE 1: One Empty Line After
     CLOSED: [2016-06-28 Tue 21:00]
     :PROPERTIES:
     :END:


Expected Result:
* 2016
** 2016-06 June
*** 2016-06-14 Tuesday
**** DONE 2: Two Empty Lines After
     CLOSED: [2016-06-14 Tue 21:00]
     :PROPERTIES:
     :END:
*** 2016-06-28 Tuesday
**** DONE 1: One Empty Line After
     CLOSED: [2016-06-28 Tue 21:00]
     :PROPERTIES:
     :END:


​The following produces the expected result on "Minimal Example":
1. Archive second TODO "2".

2. Archive first TODO "1".


However, I personally think the Desired result would be (two (2) empty
lines, that is, respect the original number):
​* 2016
** 2016-06 June
*** 2016-06-14 Tuesday
**** DONE 2: Two Empty Lines After
     CLOSED: [2016-06-14 Tue 21:00]
     :PROPERTIES:
     :END:


*** 2016-06-28 Tuesday
**** DONE 1: One Empty Line After
     CLOSED: [2016-06-28 Tue 21:00]
     :PROPERTIES:
     :END:



Could you provide an ECM?
>
> Thank you.
>
> Regards,
>
> --
> Nicolas Goaziou
>