Hi Sarah! Your example is missing a few words here and there, but luckily I found the original text you had found this in.

The translation goes something like this:

Lexemic variation has further been increased by the fact that there have existed words beginning with three consecutive consonants, where (letter 's') has been prefixed to a word already beginning with a combination of two consonants, where the first letter is 'k', 'p' or 't'.

Often the variations with- and without- 's' have been used interchangeably, either (differing from) person to person, or even with the same person speaking.