The movie and TV series are not actually named "Twelve Monkeys", but "12 Monkeys", although the movie is sometimes marketed as "Twelve Monkeys". The tag should probably be renamed.
Should we split the tag into two tags, one for the movie and one for the book?
Use the usual naming strategy.
Simple. We should use our usual naming strategy for the film and call it 12-monkeys-1995
For the tv show I propose we leave it as [twelve-monkeys] since [twelve-monkeys-tv] looks silly. We should call the TV show twelve-monkeys-2015 as that is coherent with our tag system for other shows (e.g. the-flash-2014).
Swap "12" for "Twelve" as need be, I don't know what it really it should or would be called.