I agree that the questions are effectively duplicates. Being paralyzed by fear, and scared motionless are conceptually as synonymous as I can imagine questions being.
My main criticism with what happened here is that the old question was closed (albeit for an unusual reason for this question category), and the new question had much more effort put into elaborating the concept. Moreover, the newer question seems like it's also a candidate for the translation tag, and seems like it might actually help more people. It's a much better example of how a question should be asked, and I think tchrist should recognize that given his answer to How Do I Write Good Answers? I say this because the newer question does seem to follow Yoichi's Oshi's example, or at least it does much moreso than the old one. (Yes, tchrist's answer attracted votes against it, but I think that is for reasons other than this advice.)
Now I do admit that there is a certain sort of logic to preferring the older questions too though. Namely, it encourages questioners to actually check for prospective duplicates before randomly asking the same question, and prevents fraudulent duplicates. Generally speaking, I would prefer the older question.
However, the plurality of factors seems to favor changing the canonical question, especially since all of this should most especially be considered with the apparent philosophy that closed questions are candidates for deletion and deleted questions don't count as duplicates. See this post by community moderator Grace Note on Information Security Meta and the following quotation from our help center's page on question deletion:
Over time, closed questions that are not useful as signpoints to other questions may also be removed, as well as questions which have no significant activity over a very long period after being asked. If you want to improve a question to keep it from being deleted, click the edit button beneath it.
This is not exactly my favorite policy, so I am hesitant to cite it, but that is strictly because I think preserving good answers may be worthwhile even if the question itself is bad and should be deleted. The ultimate goal of the website is to build a library of high quality answers afterall, as indicated in the tour:
English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. It's built and run by you as part of the Stack Exchange network of Q&A sites. With your help, we're working together to build a library of detailed answers to every question about English language and usage.
However, considering that the questions were being merged anyway, all of the answers would have been preserved too. With that in mind, I think preference should have been given to the new question when merging them together like this.
Granted, unlike Mari., I'm not factoring in how rep. is affected by the merging. I don't know how that works.
Regarding the next candidate, I would personally leave it alone. Although it is similar, and some of the same answers may apply, it does not regard a specific emotion, but just emotion generally. Perhaps this is a finer distinction than some people would make, but it's there.