Updated!

perl -e"print substr$_,6 for sort map{sprintf('%02d'x3).$_,/^(\d+)-(\d
++)-(\d+)/} <>" junk
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broquaint pointed out that in my enthusiasm for golfing this I forgot to reorder the date components.

P:\test>perl CON junk
print substr$_,6 for sort map{/^(\d+)-(\d+)-(\d+)/
&&sprintf('%02d'x3).$_,$3,$1,$2}<>
^Z
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Not so good, but at least it works this time! Someone can do better than that I'm sure.