Activity stream: gather "downloaded information"

Problem
Too many "downloaded" events are displayed.
Most of them do not represent real downloads but document view.
They add unimportant information when they repeat the same information with a close timestamp.

Goal
Filter out, client side, 'downloaded events from same user and with a date distance < 24 h. Only the first should remain in activity list.

Note
In "same" event, show the most recent