The main-arm swing or "use" animation will sometimes play twice when interacting with many things, such as gates, beds, lecterns, and so on, as well as when placing blocks.
Have only been able to replicate the issue on servers, so may be related to latency.
Attached video is on a creative server but have experienced the same thing on two survival servers as well.
Thank you for your report!
We're actually already tracking this issue in MC-163910, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.
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