If you rebuild it like show in the pictures, it will "count down" very fast and overwrite the stronger redstone signal with the weaker one, until it is at 0, then the redstone with the current of 15 will overwrite the 0 with 14 again and so on.
(If some complain about this as a cool feature, you can achieve this effect without using bugs 😛)
Duplicate of MC-5742, please use the search function to see if your bug has already been submitted. Currently over 42% of tickets are being closed as duplicate.