I know most people probably don't care, but why do you have to call the series Anno 1602/1503/1701 A.D.?
I know that the original german name is Anno <Year> and some international editions were called <Year> A.D.
But using both at the same time is just redundant.
"Anno" is Latin for "In the year" and A.D. is an abbreviation of "Anno Domini" which in turn means "In the year of the Lord".
So "Anno 1602 A.D." basically means: "In the year 1602 in the year of the Lord". Doesn't sound right, does it?

So is it possible to change the name either to the original German version or the international one, but not both?

I am sorry if this post appears pedantic, but this really bothers me.

What is wrong with you, seriously?

Anno is the name of the series, 1602 A.D is a specific game in the series.

Example :
Battlefield : OCD, Call of Duty : Modern Assholes, Anno : 1503 A.D. When we say Anno we refer to the whole series.

Stop that and go see a psychiatrist. Be glad they added these games to the list, and quit complaining about trivial CRAP!

This *is* a valid question.

German name "Jahr 1602" isn't very marketable so the game was released under Anno 1602 name to make it easier to sale on European market. A year later the game was published in America under even more romanized name 1602 A.D. The positioning of A.D. isn't strictly traditional but acceptable in modern use.

Where do you see doubling 'year' word? I can't find that anywhere.

Hofzwerg a point. On the (English) website the games are listed as ""Anno 1602 A.D.", "Anno 1701 A.D." and so forth, same with the installers, start menu entries etc.

In Germany and most of Europe the series was just called "Anno XXXX". In the US they released all games up to 1701 as "XXXX A.D.", then switched to "Dawn of Discovery" for 1404 and then again switched to the original title for 2070. It's a confusing mess:
https://en.wikipedia.org/wiki/Anno_%28series%29

GOG simply combined the different regional names of Anno, resulting in a nonsensical name ("Anno 1602 Anno Domini"). It's rather stupid. Please stay polite to other members of the community. No need to get aggressive. :)