No, doesn't work :(
It occurred to me that the code should refer to how the date is set out in the database "Y-m-d" so I altered that but it still doesn't work.
This is the code that I now have on the site
<?php if ($row_rsCiviEventResults['end_date']!="" || date("Y-m-d", strtotime($row_rsCiviEventResults['end_date'])) != date("Y-m-d", strtotime($row_rsCiviEventResults['start_date'])) ){ ?>
I'm sure it must be something simple that I'm missing here.