The CBI is silent on that situation. I don't know of any other subordinate policy documents (and a FAQ doesn't quite cut it).
I suspect that the intent is to not provide dual reimbursement. However, the devil is in the details. What follows is my interpretation of the somewhat terse FAQ and the CBI.
If the scholarship/bursary is unrestricted, then there is not problem - you got $4K and spent it on accomodation / food / alcohol / whatever; you're claiming reimbursement for tuition and eligible expenses paid for out of "other" money. (Yes, the funds are co-mingled in your bank account, but that's not relevant here).
If, on the other hand, the scholarships and bursaries you receive are applied immediately to your tuition, then you can only claim the amount you paid after the reduction.
In other words:
If your tuition bill reads:
Tuition - Basket Weaving 101 - $6000
Less Scholarship ($4000)
Amount owed $2000
Payment ($2000)
Balance 0
Then your reimbursement would be 50% of the $2000 you actually paid. If, on the other hand, the scholarship/bursary money went directly to you without conditions, the full amount of your basket weaving would be claimable (subject, of course, to the limits in the CBI).