From The TimeSplitters Wiki

Hey, isn't just coindence ,but wasn't "the early prototype of R-100 series" created in 2052 (Future Perfect (It was said by Anna in the final 2052 level "You Genius U Genix")). That would basically make R-108's appearence in 2020 impossible because his prototype may have not even existed yet.

- Crows

Haha! That's very true, there are a few things like that dotted around the series! But that's the problem with time travel, tis very complicated...

You could add that to the "Trivia" section of the article if you want =)

- randomwolf1