If you take a look to any course/recent.php page with PHP5, every item seems to be repeated n times (for example, in a forum with 3 posts, I see the same post three times).
Some new Object need to be created in xxxxxx_get_recent_mod_activity() iterations to avoid this effect under PHP5.
It's the same cause than
MDL-2073 (and the same solution should be applied to every xxxxxx_get_recent_mod_activity() function in each module.
I'll do it (just waiting for your confirmation, Martin).