For some reason, any event I put in for October 31, 2013 shows up every day in November as well. The date listing on the duplicate events is still October 31 — the duplicates only show up in the calendar view, not in the events list in my dashboard.
Originally, the event falling on 10/31 was a recurring (weekly) event from September, but I deleted the last day, and put in a separate event for 10/31 with the same outcome.
Unfortunately you’ve hit on a known bug with the current release of the plugin (similar things can happen on other months, too).
What can help in some cases is adjusting your date/time settings through the general settings screen in WordPress. If it is set to a city such as Los Angeles then try changing it to the corresponding offset, such as UTC-8 – or vice versa.
We have fixed this in 3.0 which will be our next release and has just completed beta testing (so we’re close to release).