RE: shouldn't substitute-command-keys remove duplicates?

["Drew Adams" <drew.adams@oracle.com>]

As an example, filecache.el does this (via ;;;###autoload):

(define-key minibuffer-local-completion-map
            [C-tab] 'file-cache-minibuffer-complete)
(define-key minibuffer-local-map
            [C-tab] 'file-cache-minibuffer-complete)
(define-key minibuffer-local-must-match-map
            [C-tab] 'file-cache-minibuffer-complete)

This is in spite of the fact that minibuffer-local-map is
the parent of minibuffer-local-completion-map and
minibuffer-local-completion-map is the parent of
minibuffer-local-must-match-map.

The first and third bindings here are therefore superfluous,
but they serve to show that (substitute-command-keys
"\\{minibuffer-local-must-match-map\\}") doesn't remove the
duplicate entries:

minibuffer-local-must-match-map
-------------------------------

Local keymap for minibuffer input with completion, for exact
match.

key             binding
---             -------

C-g             abort-recursive-edit
TAB             minibuffer-complete
C-j             minibuffer-complete-and-exit
RET             minibuffer-complete-and-exit
ESC             Prefix Command
SPC             minibuffer-complete-word
?               minibuffer-completion-help
<C-tab>         file-cache-minibuffer-complete
<C-tab>         file-cache-minibuffer-complete
<C-tab>         file-cache-minibuffer-complete
<down>          next-history-element
...

> From: Drew Adams Sent: Thursday, March 20, 2008 9:47 PM
> Shouldn't substitute-command-keys remove duplicates?
>  
> If you explicitly bind a key to the same command in both a
> keymap km
> and its parent pkm, and then you call this, the binding is
> written
> twice:
>  
> (define-key km  "a" 'foo)
> (define-key pkm "a" 'foo)
>  
> (substitute-command-keys "\\{km\\}")
>  
> key             binding
> ---             -------
>  
> ...
> a  foo
> a  foo
> ...
>  
> In GNU Emacs 22.1.90.1 (i386-mingw-nt5.1.2600)
>  of 2008-01-30 on PRETEST
> Windowing system distributor `Microsoft Corp.', version
> 5.1.2600
> configured using `configure --with-gcc (3.4) --cflags
> -Ic:/gnuwin32/include'