The first name was Vasco Pamplona. Vascones were the native tribe in that area. So, I think he didn't live in the city (which was controlled by the French at the time) but on the boroughs. That would justify not having documents anywhere about this person. Given that they spoke a different basque dialect, I wouldn't be surprised if his name wasn't easy to pronounce. He might have just adopted a new name when he moved to Portugal. I am guessing that the Portuguese didn't know his name and nicknamed him as Vasco de Pamplona.