Hi there,
If you think that you have to repeat 11 to understand 12 then surely give it a try.
Or if you think you can manage both together then don't repeat.
But in my opinion you must repeat 11 sobthat you could actually gain the real knowledge as passing doesn't matter if you don't have the knowledge.
I hope this help
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile