Remember to cover the basics, that is, what you expected to happen and
what in fact did happen.  You don't know how to make a good report?  See

     http://orgmode.org/manual/Feedback.html#Feedback

Your bug report will be posted to the Org-mode mailing list.
------------------------------------------------------------------------

In the following table:

| [2016-07-03 Sun]--[2016-07-04 Mon] | 1d | d   |
| [2016-07-03 Sun]--[2016-07-05 Tue] | 2d | 2 d |
#+TBLFM: $3=$2

The second column is computed by pressing C-u C-c C-y. This sequence
calculates the time difference between the time-stamps in the previous
column and inserts the difference in the current column. This is fine.

Now, for the third column, I insert the formula listed at the bottom of
the table. Once applied, the result of the formula for the fist row is
just "d" instead of "1d". So, it seems that the value is not copied
correctly.

This seems to work fine if the time-stamp range is greater than one
day. Also, for the second row, the value is copied correctly but there
is an extra " " inserted between the number and the "d" letter. This
might not be desirable.

Appending "D" at the end of the formula, yields the same result:

| [2016-07-03 Sun]--[2016-07-04 Mon] | 1d | d   |
| [2016-07-03 Sun]--[2016-07-05 Tue] | 2d | 2 d |
#+TBLFM: $3=$2;D

I also tried appending "T" at the end of the formula:

| [2016-07-03 Sun]--[2016-07-04 Mon] | 1d | 00:00:01 |
| [2016-07-03 Sun]--[2016-07-05 Tue] | 2d | 00:00:02 |
#+TBLFM: $3=$2;T

The numeric value is copied correctly but the days are now changed to
seconds.

I attached a dribble file which allows you to reproduce the first row in
the first table.

Emacs  : GNU Emacs 25.0.94.1 (x86_64-redhat-linux-gnu, GTK+ Version 3.20.4)
 of 2016-05-18
Package: Org-mode version 8.2.10 (release_8.2.10 @
/usr/share/emacs/25.0.94/lisp/org/)

current state:
==============
(setq
 org-tab-first-hook '(org-hide-block-toggle-maybe
              org-src-native-tab-command-maybe
              org-babel-hide-result-toggle-maybe
              org-babel-header-arg-expand)
 org-speed-command-hook '(org-speed-command-default-hook
              org-babel-speed-command-hook)
 org-occur-hook '(org-first-headline-recenter)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-confirm-shell-link-function 'yes-or-no-p
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-src-mode-hook '(org-src-babel-configure-edit-buffer
             org-src-mode-configure-edit-buffer)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-babel-pre-tangle-hook '(save-buffer)
 org-mode-hook '(#[nil "\300\301\302\303\304$\207"
           [org-add-hook change-major-mode-hook org-show-block-all
            append local]
           5]
         #[nil "\300\301\302\303\304$\207"
           [org-add-hook change-major-mode-hook
            org-babel-show-result-all append local]
           5]
         org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-ctrl-c-ctrl-c-hook '(org-babel-hash-at-point
              org-babel-execute-safely-maybe)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers
          org-cycle-hide-inline-tasks org-cycle-show-empty-lines
          org-optimize-window-after-visibility-change)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 )