Slitherine

Operation text shows that increased growth from cloning lasts 10 turns.

After launching operation, on city it shows that accelerated growth is only for 8 turns.


Medium game pace was used.

Did you launch it on a base that didn't already have accelerated growth?

^Like BlueTemplar suggests you're most likely casting cloning on a city that already had it running, thereby wasting it.

That's one thing I've been requesting for a while now: Casting cloning on a city already running cloning should extend the cloning time. It's really confusing and creates a lot of micromanagement how it is now where any subsequent cloning casts are simply ignored (and the production spent on the cloning operation wasted).

Hmm... it's possible.
I did got later city with duration of 10, so this was a one time occurrence.