Alright guys, here’s an update of the situation:
Long story:
Found out what went wrong. The new ability to enable / disable ajax update
via Settings / WordPress Popular Posts / Tools / Data tools is the culprit.
For some reason I’m still trying to understand and correct, when viewing any single post / page it ocassionally also updates the views count of another post / page simultaneously – hence why it is doubling the count of some entries.
Bad news is that after the update to 2.3.0 all views count added to the WP DB tables are wrong. The only workaround to prevent it from continuing doubling the views count is to enable the AJAX update since the problem occurs only when it’s disabled.
I will remove that feature on the next upgrade until a fix is ready, so please keep an eye on your Plugins’ page.
Summary: (for those who don’t feel like reading a lot)
Problem with views count is generated by the new ability to turn on / off the ajax update via Settings / WordPress Popular Posts / Tools / Data tools. Enabling AJAX update “fixes” the problem, it occurs only when it’s disabled. A plugin update will follow, this feature will be removed until a fix is ready.