I prefer adding it as an alias as mfmeulenbelt said, not so much adding a second (and third and fourth) artist entry the way thomnottom’s example shows.
IMO, there are very few times an artist needs a 2nd entry.
mfmeulenbelt’s (and my) suggestion is just to have the real name listed on the artist entry page.
But if there a place he is credit as something other than Asu, that is what the “credit as” box is for.
Let’s say, as example, his writing credits are under his real name. You can put Asu in the box the way you normally would, and then put Alexandru Gabriel in the credited as box.
It will display as Alexandru Gabriel but will link to the Asu entry.
I just fixed up this entry that has everything I am talking about.
Entry name is different than the real name, which is listed under the aliases tab (many of the aliases are spelling issues, there just for search purposes). He is credited in multiple ways, which can be found listed under the relationships tab.