As per CIC, only the highest degree needs to be evaluated. It is clearly mentioned in all their online guides. The reason people send Bachelors as well as Masters is because from Asian countries, sometimes WES will not recognized the Masters as a Masters degree and if you dont send the bachelors, then you cannot claim Two or More points. And then you will be left with nothing. So not to take a chance, people send both.
However, if you do the equivalency test on WES site and your university is a reputed one from a First world country, then WES will directly evaluate it as a masters and then you do not require the Bachelors.
I have a British MBA from a good reputed British University and that was the only one sent to WES and they evaluated it correctly as a Masters. That's all that is required. CIC does not care what you did before your masters since they only want the highest degree evaluated and its is WES responsibility to ensure that it is a genuine masters. If WES gives you masters, that's all you need.
All this is in the CIC website. Besides taking advice from people here, please also read the guides yourself too. Thank you.