Portal 2 Coop Story
Portal 2 Coop Story 7,1/10 9021 votes
Portal 2 Wiki
The only reason why the order of playing could matter is the timeline, as SP takes place before the MP.But in terms of plot and potential spoilers it isn't a problem at all as Thomas mentioned. In player training however, you aren't shown how the new game elements work but only instructed. But this should still be fairly easy to experiment with the game elements and thus a new player should be able to still complete the MP with ease.All MP characters are seen in SP; so, play SP later if you want to know where the robots come from.