aah interesting, it shouldn't have unlocked anything then since it's just supposed to save when you go to the next mission. Confusing... Either way, you could just ignore those unlocked levels 11 and 12 then, unless you already completed 11. I'd advise you to replay mission 9 if that was the last one you actually completed. Otherwise you might end up having a hard time beating higher missions if you just have the soldiers and equipment from level 9.
Or you can go ahead and just try to continue from the last unlocked level and see how it ends up ^^. It's really an interesting issue.
"The absence of rules is the enemy of art." ~Orson Wells
