This is one way, often violins, cellos and double bass can be mixed up and violins can be on both left and right. It's called the antiphonal arrangement.Clearly there was an evolution of having higher pitched instruments on the left, the lower toned instruments on the right and horns and percussion in the back.
Some have speculated that conductors who were more conscious of the recording once stereo era started, broke from the antiphonal to the violins on the left and lower toned instruments on the right.
But today at concerts I see both. Especially a lot of Beethoven is antiphonal.