I was just checking when Series 2 would start and came across this :
Each episode is filmed twice, once in Welsh and again in English. And it’s not just the languages that are different; the English BBC audience and the Welsh S4C audience see a whole different version of each episode. Because S4C has adverts, each Welsh episode is just 48 minutes, while BBC viewers get approximately 10 minutes of extra drama.
As a whole the two versions are tonally different,” added Myles. “We have two different editors and two different execs.
Un Bore Mercher and Keeping Faith are so distinct from one another, in fact, that scenes are reordered and the story itself plays out in a different order in each version, explained writer Matthew Hall
And in case you were wondering – no, the actors don’t get paid twice.