gitk and duplicate commits

If I pass in the same commit multiple times (possibly
under different names) to gitk,
it will echo the warning from git-rev-list
(sort_list_in_merge_order: duplicate commit 82e3583b9426c193659a4c1315d6a3b3cee11dce ignored)
and then simply stop.

Surely this can be handled more gracefully.

Note that I do want to be able to pass the same commit
multiple times.  At least, I don't want to check
whether two "branches" happen to refer to the same commit.

skimo