phpbb_fbc_statstable can occur for the same country a second apart.
I still don't understand why the
core.user_setup_afterevent seems to be called more than once when accessing a page. I tie into the event to prohibit or allow access by country. One workaround it simply to see if there is a similar statistic logged a second earlier and if so not save the statistic. This seems to work but might potentially create an under count of statistics on very highly trafficked boards. For example, it's possible with some sort of denial of service attack coming from a country like Belarus only one page request will get recorded over two seconds when there really were more than that occurring in a very short period of time.
Toward that end I have added a configuration variable where this value can be set in the extension's settings page, defaulting to one second. It is possible that if you have a slow database you might want to up the setting to two or more second. Zero disables it.