Pronounced the same

Search for "Skechers" footwear today and you'll find that's the spelling of all the references to the popular brand. However, those who are experiencing the Mass Memory Discrepancy Effect claim it used to be spelled as "Sketchers".

There are one or two references to the "Sketchers" spelling, but because most people would pronounce both versions the same, they could be just thinking the real English word "Sketchers" must be the correct one and have unconsciously fixed the spelling in their heads.

There are also exist genuine typos such as here and here, which is understandable with the pronunciation being the same. 

Skechers USA

Founded in 1992 and Headquartered in Manhattan Beach, California, Skechers is the third largest sports footwear brand in the USA. It has 2,650 locations worldwide, employing 11,800. It's not without controversy, either, because in 2012 it settles a $40m class action lawsuit regarding misleading advertising.

The Sketchers/Skechers issue is one of the better known spelling Mandela Effects, and the usual caution around any global brand tinkering with its very name, for any reason at all, applies. Millions are invested in this kind of marketing which usually pays dividends in the long term due to brand loyalty, so it would never be changed without good reason.

People experiencing this Mandela Effect say the word just looks "plain wrong" without the "t". One idea is that at first glance, the word doesn't resemble any other but would do if the "t" was added, so at a subconscious level the brain tries to correct this unfamiliarity by adjusting it into a word it does know, which is "sketch", hence the "t" gets added. Clearly, people who sketch, i.e. Sketchers, are nothing to do with running shoes, yet the tendency for the brain to resolve word irrespective of it's meaning remains strong, and possibly in some people so strong the new word becomes the dominant memory.