I had to do the English test as part of my Canadian permanent residency and it was oddly terrifying. English is my first (and only) language.
Luckily it turns out I can speak the English reel gud. I now have a certificate to prove it!
There were other people in my test group who couldn't follow basic instructions that were given out before the test ("Please wait over there", etc.). I imagine they didn't do so well.
I didn't take an English test when I applied as a skill worker for permanent residency (it's not my first language). It was heavily recommended to do so but I wrote a page outlining my work experience in the US, other test results etc and I didn't have any problem.
It was a bit risky because it was up to the official reviewing the application to accept it or not but I didn't feel like spending a grand and flying to another city for a day to take a test.
I don't know if things have changed and now a test is required without exception; all data indicate that not knowing well the country's language(s) is the main factor for not succeeding in it as an immigrant.
As someone that speaks English "reel gud" I can understand that the test was "reeli harrd". It's amazing how many people have problems with tests of their own first language just for the fact that they have never learned grammatical rules and that they can't distinguish between "standard" language and a local dialect they are used to. After all, it's native speakers that are guilty of "their" and "there's" confusion.
For the skills-based immigration (not the startup immigration) you're right, you can do both. You can get up to 16 points for your primary language (out of [English|French]), and up to 8 points for the other one. So it can be worth getting even a very low qualification for your second language, if you need to tack on a point or two to reach the threshold.
Luckily it turns out I can speak the English reel gud. I now have a certificate to prove it!
There were other people in my test group who couldn't follow basic instructions that were given out before the test ("Please wait over there", etc.). I imagine they didn't do so well.