Using same evidence for two criteria counts as two evidences?

I’m not sure how the form’s interface works and it isn’t clear from the Tech Nation’s guide

No, it doesn’t count. You will see a field where you should list your documents for the criteria selected For example, if you have 10 documents. It can be

MC: 1,2,3,4,5,6
OC1: 5,7,8
OC2: 6,9,10

Note that it’s still 10 documents altogether.