OK, I think I've figured it out (maybe).
The CAW2116 is the 2010 Singapore GP edition. As noted in these two articles released in Aug 2010, the watch was made to celebrate the 3rd running of the Singapore GP in 2010, limited to 100 pieces (numbered).
https://www.watchprosite.com/news-c...-150-years-of-watchmaking/112.643731.4036731/
https://themonsieur.com/2010/09/08/singapore-gets-its-own-tag-heuer-monaco/
The CAW2117 seems to be from 2011. As seen in the Calibre11.com article and limited to 400 (non numbered, no "Singapore Edition" marking on caseback). Although I think it was just a run over into the next year, rather than being made for the following year's 2011 race.
This current listing also shows the CAW2117 to be from 2011, although I'm more trusting in Calibre11 as a source.
https://www.christopherpoel.co.uk/product/tag-heuer-monaco-singapore-grand-prix-2011/
Whatever the real story is behind why TAG made two slightly different versions of the same watch, the CAW2116 is surely the more collectable one!
👍