SimilarSites Plugin and Unknown Fact

https://addons.mozilla.org/tr/firefox/addon/tamper-data/I used SimilarSites Firefox plugin to get same of using web site. This plugin works background of firefox. So, i notice that this plugin send some reports to its web services. These reports are related to log on to the active website session information. These information sents this web service http://app8.similarnet.com/similarweb/SimilarWebService.svc , when you entire any web site. (You can check with Tamplerdata). They dont report to collect these informations with what purpose.