Excel really isn't made to easily work with page breaks. Page breaks depend on
the printer (which depends on what the user chooses). It can get pretty messy
pretty fast.
If you're willing to just show the first value and hide the duplicates (no
matter where they occur, you could use conditional formatting--like Debra
Dalgleish shows at:
http://contextures.com/xlCondFormat03.html#Duplicate
I've seen users who use a separate column (and hide the original column) so that
they could show ditto marks.
Say column A contains your dates. Insert a new column B and use a formula like
this in B2 (headers in B1):
=if(a2=a1,"""",a2)
and drag down (and hide column A)
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Personally, I like to show the information on each line. I find it easier, er,
less work.