Did a medieval flying monk spot Halley's comet, twice? It's complicated

The historical account of Eilmer of Malmesbury, a Benedictine monk from the early 11th century, suggests he may have witnessed Halley's Comet twice, though the exact dates remain debated. William of Malmesbury, writing around 1125, documented Eilmer's famous attempt at flight from a 150-foot tower using homemade wings, an event that resulted in broken legs after gliding approximately 600 feet. William also recorded Eilmer's observation of Halley's Comet in 1066, where the monk remarked, "It is long since I saw you." This statement has led some historians to infer that Eilmer also saw the comet during its previous appearance in 989, which would place his birth no later than 984 and his flight attempt between 1000 and 1010. However, James Aitcheson of the University of Leicester challenges this interpretation in a paper published in the journal Notes and Queries. Aitcheson proposes that Eilmer might have seen the comet of 1018 during his youth instead of the 989 sighting. If this is the case, Eilmer would have been born significantly later, and his flight experiment would have occurred between the 1020s and 1040s, making the precise timeline of his life and observations a subject of ongoing historical inquiry.