I manage 2 websites for two brands that are owned by the same company. The websites are very similar in the way that they look and function. In November of last year, they were 1 and 2 for most of our keywords. After the Dec. algorithm update, they both went down. One of them slowly recovered back to #1 but the other has lost rank and is now on the top of the second page. The domain authority scores, backlink profiles, speed profiles, etc. are very similar.
I just wonder if because they look very similar and have similar content the one that has fallen is getting “flagged” for duplicate content. Has anyone else had experience in this that could offer some insight?