It's odd. While it will just be a stick-on, it is shown in the parts diagram via the VIN of a similar DS5 I had borrowed to look it up. However, looking at a photo of that car, which I know has never been damaged, it has no Citroen badge, nor is it there in photos of the back end of a few others. Maybe, it was a panel shop error in going strictly by the parts book or someone just wanted to add it? Maybe, the local dealer stuck it on to help sell it in a market where DS was unknown??? It's not 'wrong' per the parts catalogue, but that does sometimes have errors or just variations because the DS range was regarded as 'personalised'. There was an attempt to make DS a separate brand without Citroen badging, so up to you if you keep it or remove it.