The warranty time is country specific (i.e. different members of the EU have different regulations). In particular that means that the Polish distributor ArtaTech is allowed to offer 1 year only.
See posts #48
and #73 - #75
in this thread.
I have had a similar issue with Garmin GPS devices.
I even contacted Garmin's European Service Center.
I was told that their "international warranty" validity time depends on the origin of their device. No matter where you buy it, you need to know from which "distribution channel" it comes. I think I remember two cases now - if the device originates in Garmin-France the warranty is 1 year, if the device originates in Garmin-Netherlands the warranty is 2 years (I don't really remember it exactly now, I am sure about France, but I don't remember the list of countries in which their warranty was 2 years, there were not so many, however).