Count metric not counting real events


I'm using metric filter to count all events received from each server i have (separatelly).
The value i get is not real, count show a number which is higher than the real events i received.

metrics {
meter => [ "%{host}" ]
flush_interval => 30
clear_interval => 300

real event are 50 and metrics count (that is showed in kibana, all grouped) shows 430.

Am i doing anything wrong?