OS X Lion Mail.app sound effects bug

This is one of the weirdest bug that I've observed: It seems that Mail.app's audio notifications for new mail and sending mail accumulate and play in order of occurrence when I unplug external speakers. Just now it played a series of more than 100 notifications (mostly new mail notification).

It's not big enough that I want to fix it but I just wanted to know if anyone experienced something similar.

It happened on an iMac that was upgraded to OS X Lion from Snow Leopard.

I don't have an answer, but here is how to reproduce the error. Open mail.app then call someone on FaceTime.

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