1. Highlight multiple messages in the thread pane. 2. Type ctrl-p to bring up the print dialog. 3. Click the cancel button. 4. The first message won't be printed, but the other messages you highlighted will be printed, despite the fact that you cancelled.
Also reproducible on SeaMonkey (running on Linux x86_64).
Component: Mail Window Front End → Printing
Product: Thunderbird → MailNews Core
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