I think the double-testing issue is the fact that you do a language test to be able to become a citizen, and you need to meet the CLB 4 benchmark. Testing knowledge and testing language are two separate criteria that have been set out by Parliament, and we can debate their scope and whatnot, but if you're going to have a knowledge test it should be separate from the language test. You're testing knowledge.
What's happening right now is that the knowledge test, by virtue of having to be done in English or French, becomes a second language test and arguably is a language test that might be hard for someone who can otherwise pass a CLB 4. They're having problems passing the knowledge test because of the language, not because of the knowledge.
Test the knowledge separately from the language would be my recommendation.