Summary of Jordan Penkower on reading Zekher or Zeikher Amalek
It appears here with permission, with some additions by the Seforim Blog editor. It is common practice in most Ashkenazi congregations to read the words z-kh-r Amalek, in Deut. 25:19, twice: once with a tzere under the zayin (zeikher) and once with a segol (zekher). Sephardic congregations, however, who do not distinguish between the pronunciation of these two vowels, read it only once, and they point it with a tzere. What is the origin of this practice, when did it…