This reverts commit 9955048aec.
This commit broke collections that had children under each of the
the duplicate names - it renames one of the decks, but the children
of the renamed deck are left without a parent, causing an error like
line 235, in deckDueList nlim = min(nlim, lims[p][0])\n\nKeyError('..)
Rather than a more complicated approach, I think it's safer just to
leave the case or normalization-differing decks around for now, and
we can normalize things properly in a future schema upgrade.
5418af00f7