shouldn't substitute-command-keys remove duplicates?

[Drew Adams]

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'