Many shuls read the last pasuk of Parshat Zachor twice, once with "zeicher" and once with "zecher", based on a (possibly not so valid) doubt in how the word should be read.
The Tikkun Simanim brings another uncertainty on the side: their "default" unsourced version (which is the one I've heard most often, also followed by Koren) has אֲשֶׁר־יְהוָ֣ה אֱ֠לֹהֶיךָ, while they quote the Keter Aram Tzova as having אֲשֶׁ֣ר יְהוָֽה־אֱ֠לֹהֶיךָ (this is followed by the Ish Matzliach tikkun and Artscroll). Of course this doesn't change the meaning, but then neither does zeicher/zecher.
What is the source of these versions? Has anyone recommended to read both (either instead of or in addition to zeicher/zecher)?