Duplicate content error happens when the FB pixel has not been setup properly or has been duplicated.
FB base pixel should be setup at decision tree level (or via GTM).
Then only fire FB events on the node.
There is NO need to add the whole pixel into the node level tracking again. This will result in a duplicate FB error because the base pixel is firing at the decision level and also at the node.
This setup in INCORRECT…
Please see Module 10 for more details in particular these 3 units.