From a technical standpoint I understand, from a logical one, I would like to see them cross-marked. Let's say most people mark in the forum. Then the author of the resource is not getting the "Love" they deserve on the resource side, and people judging by reaction will get the wrong impression.
It follows the current logic anyway. The content is a duplicate. So why not the reaction to said content?
Edit: Watching should not affect it. If you watch one, the other, or both, still... they get both marked if you add a reaction. Alerts; perhaps that would need some thinking. Since it would be marked twice, and the author would receive an alert for both, choose one: the resource wording.