So we found instances of books with an ISBN and a UPC, and books with two ISBN, but can we find non-book products with two GTIN codes? Yes, we can. Many electronic goods are now sold globally, but often contain multiple national codes, all of which are part of the GTIN system. Case in point: the HTC manufactured Google Nexus One desktop dock has both a EAN (4710937336078) registered in Taiwan and a UPC (0821793004965). I don’t fully understand why this is needed, clearly you need a UPC for being able to sell the device in the US, where there might be old system that cannot handle the 13 digit codes. But then why bother with an EAN code? In theory systems that can handle EAN can implicitly handle UPC codes.

Still these weirdnesses are only caused by the old UPC legacy issue? Not always: there are cases where a box contains two codes in the same national prefix space. Here the example is the Vodafone 802SE that I owned while I lived in Japan, the box harbours two JAN codes: 4908993111252 and 4908993111252, both registered with ソフトバンクモバイル (Softbank Mobile). Maybe one was for the actual phone, the other for the phone subscription.