url duplicate with random numbers

Hi Guys!

I’ve this bad issue on my wp blog.
For every url page, example:
http://blog.lecobottega.it/2015/12/04/decorazioni-di-natale-fai-da-te-dal-riciclo-creativo-della-lana/
if you add random numbers at the end of url, example:
http://blog.lecobottega.it/2015/12/04/decorazioni-di-natale-fai-da-te-dal-riciclo-creativo-della-lana/4555534232322/
So, the page loads the same, thereby generating duplicate url.

What can i to to fix this?

I tried to disable all plugins but nothing changes!

Help me, please 😉

Valerio