I want to keep only one English keyboard layout (US keyboard) but need spell checkers for English (United States) and English (Australia), probably English (United Kingdom) as well. When I added all flavors I end up with multiple entries for US keyboard layouts (this is what I use for all English types) in my list for input keyboards that mess up this list. I switch between other non-English languages and don't need this list to be any bigger than number of languages I use by merely increasing occurrences of same keyboard layout (or unneeded layouts).
Please see section D in this Microsoft page: https://answers.microsoft.com/en-us/ie/forum/ie11-iewindows_10/spelling-correction-and-checking-in-internet/a1321c59-3623-49a2-8fce-388ecc2cb057
In Win 10 the spelling is built-in to Windows 10 rather than just the browsers.