[Plugin: WordPress Download Monitor] Problem with Statistics

Hello I have the following issue with the plugin

Statistics in the monthly statement some months appear to me twice, as in this screenshot.

http://img88.imageshack.us/img88/6346/zrzutekranu20120716o184.png

Can someone help me to fix this?

Address of my website is http://Eudezet.org/

http://wordpress.org/extend/plugins/download-monitor/