Pinyin input on Mac 10.12.3+ duplicates text

[DarrenFordQSR]

When the pinyin keyboard is activated on a Mac running a later version of Sierra (both Chrome and Safari have been tested), entering text via the Pinyin input source duplicates the characters typed.

This seems to have happened somewhere between 10.12.0 and 10.12.5

Steps to reproduce :-

On a Mac running 10.12.3 or above,

1. Enable the pinyin input source (System Preferences > Keyboard > Input Sources > Add Chinese simplified source)
2. Visit the WebODF demo website (http://www.webodf.org/demo/ci/wodotexteditor-0.5.9/localeditor.html) using Safari or Chrome on Mac
3. Enable the pinyin keyboard (via the keyboard input source in the main menu)
4. Start typing characters. When you hit space (which accepts the pinyin characters) the WebODF editor accepts the characters, but doubles them

See video of the issue in action here :- http://www.giphy.com/gifs/3o7btQPRhjV7qBsBNu

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