This error isn’t really an error, I guess that’s why they called it a “message”, and is caused by instruments within the Instrument List sharing the same channel.  Finale prefers all of the instruments, even left hand/right hand piano parts, to be on separate channels for optimal playback.  In the most recent versions of Finale the instrument channels are set-up for you by Finale, pre-2005 versions did not set unique numbers to duplicated instruments , so the error was quite prevalent.   To fix the issue just go up to your Window Menu and Select your Instrument List.  Within the Instrument List Window you will have to change the channel using the Instrument Column.

Here is how:

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There is a default setting within the Human Playback Preferences that will automatically diminuendo long notes.

Of all of the Human Playback Settings this is my least favorite because it just isn’t smart enough from a contextual standpoint.

Here is how you can turn it off:

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