16 times Taleb and 13 times Nassim. What's happening hear, is there another Nassim?
From looking at the scripts, it appears first and last names (actually, all capitalised words I think) were counted separately ("Neal: 11, Stephenson: 11" and "Munroe: 13, Randall: 11", etc) and first names were handedited out (so that's why both Nassim and Taleb are on the list).
The answer is somewhere between "Nassim Taleb was quoted 16 times, and three of those times the attribution was just 'Taleb'" and "Nassim Taleb was quoted 13 times and was mentioned in three other quotes (since he's a controversial figure)".
Here is the 2013 edition of the Best of Rationality Quotes collection. (Here is last year's.)
Best of Rationality Quotes 2013 (400kB page, 350 quotes)
and Best of Rationality Quotes 2009-2013 (1600kB page, 1490 quotes)
The page was built by a short script (source code here) from all the LW Rationality Quotes threads so far. (We had such a thread each month since April 2009.) The script collects all comments with karma score 10 or more, and sorts them by score. Replies are not collected, only top-level comments.
As is now usual, I provide various statistics and top-lists based on the data. (Source code for these is also at the above link, see the README.) I added these as comments to the post: