This merger had two practical effects. First, my answer to the earlier question (from 2017) now appears under the former question (which was posted on June 3, 2020, and closed a day later as a duplicate), although my answer doesn't actually address the question of whether "a comma splice is always a mistake." Second, the earlier question has been closed (as merged) and yet the later question has not been reopened, despite the fact that the question that it supposedly duplicated has been merged with it and no longer exists as an open question.
My question here on Meta isn't about why the 2020 question was chosen as the postmerger collection point for answers to the two questions, despite its being three years younger than the question that I originally answered. I assume that the answer to that question is either (1) the 2020 question attracted two answers while the 2017 question attracted only one answer or (2) the moderator who handled the merger considered the 2020 question likely to be more interesting to future readers than the 2017 question.
Rather, my question is a simple and practical one:
Why are both questions closed as "duplicate," rather than just the one whose answer was moved to the chronologically later question page on the site?
If the point of merging answers to closely related or arguably duplicate questions is to consolidate the answers in a single place on the site, it seems odd and indeed counterproductive to block further answers to the question at the consolidated location on grounds that the question there is a duplicate. I find it especially puzzling in the case of a question that had been open for six years and (as far as I can tell) never viewed as close-worthy. Was the double closure simply an oversight by the mod?