Actually, this is intentional. The date for entries that are posted on the same day are only emitted once in default s9y themes.
If you want that date for each entry, even resulting in duplicate dates, you must shuffle the {foreach} loops inside the entries.tpl file around. Once you look at that loop, you should immediately see why the date is only showed once, because the <div> is outputted inside the outer loop, not the inner loop.
Regards,
Garvin
# Garvin Hicking (s9y Developer)
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So, by "shuffle the {foreach} loops", Garvin means to move the <div> containing the date from the outer loop to an appropriate location in the inner loop.
And by "appropriate location", I mean the spot you want the date to appear in the HTML. When looking at Smarty, you see almost the HTML displayed for one entry; the extra {foreach} and other Smarty tags simply cause things to be duplicated for extra entries, with the right data substituted (like name, contents, date, and so on).
If you have any specific questions on the Smarty, we'll be here to help.