Thanks to help from @Milimetric, the issue was narrowed down to be present only on FF/Safari on Mac.
- Log in to deployment-eventlogging03:/srv/log/eventlogging
- To track/count of click events - RecentChangesTopLinks, I used grep RecentChangesTopLinks all-events.log |wc and tail -f all-events.log | grep RecentChangesTopLinks
- On RC page click on any top links (blue ones) - first two clicks will be counted (doesn't matter if the same link was clicked twice or separate links were clicked). Subsequent clicks will be ignored.