When a worker has finished harvesting (the type of resource does not matter), it may stand up / stop chucking wood twice. I.e. the animation can be played twice. This doesn't seem to always happen, but it does happen in enough cases to be notable. So far I only spotted this in multi-player games (I have not played much single player lately) but it happened both when hosting and as a client, so I assume it also affects single player.
This bug has been introduced somewhat recently, most likely within the past 20 revisions, more likely within the past 10.
I'm happy to provide a video in case this problem description is insufficient to identify the issue.