Is it possible to have in a artist page the thumbnails next to eachother instead of under eachother.
So, when you click on a artist you see two colums.
Yes, it is possible. But you would have to make quite a few changes in the template code.

OCD is quite flexible, but it requires some programming skills to reorganize the layout. The simpler tasks only require that you know your way around HTML. The more sophisticated stuff requires javascript skills.

Introducing two columns would most likely require an extra javascript in order to determine when to end the first column.