Hi,
I wrote that entry on the keyboard reference and it's out of date. There are a lot of 52G9658s that only have the single piece keycaps.
With the exception of their 1391401s and the 52G7000 (the former always had the double piece keycaps, the latter single pieces ones as far as I can see) the type of keycaps you get with a Lexmark keyboard is down to pot luck.