Yes, this bug also affects 0.14.3, tested on iOS and android. Instead of constantly closing and reopening this issue formally, I suggest some developers have a look at it. ^^
Also they are emitting redstone all the time. If the button is spawned in with setblock it works fine, only manually placed.
I have to revise my last comment. Since 0.14.3 is out, I experienced this bug only once. The server was an android phone and the client was iOS 9. Both were already updated to 0.14.3. Since then I was unable to duplicate items and therefore it seems to me that the bug is almost gone. Or it is finally gone but the android phone was not properly updated when we tested this. unlike my mate said. :X