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As far as an drops in traffic on certain dates, there's not enough traffic and data there to tell. Being that most of the terms were on page 2, traffic has been low,spotty and inconsistent. This is one of the first things I looked at but was unable to spot any obvious dates.

Rather than a penalty, they will choose one to rank over the other. You dont need a 301 and a canonical, you have one or the other, the difference being that a canonical does not redirect the user to the other page, iot just tells the search engine to give credit to the other page. It takes time for the search engine to fix tis, if you are ranking for both pages, then II would suggest you have not waited long enouth, when all is finalized, you will only find one page in the index.