The following item interactions will trigger the minecraft:item_used_on_block the criteria trigger twice:

• Strip a log block with an axe
• Wax on or wax off a copper block
• Shear a head block of growing plants (Cave Vines, Twisting Vines, Weeping Vines and Kelp)

Steps to Reproduce:

1. Download the world below and join the world. The world contains a datapack that announces to chat when you do something triggering minecraft:item_used_on_block.
2. Try the above behaviors.
3. Watch what the datapack announced in chat.
4. All of the behaviors caused twice announcements at the same time.

Why this issue counts:

Although this issue doesn't affect vanilla advancements much, some custom maps will use this trigger to listen for events and set the reward of the advancement as a function to execute commands, then immediately revoke the advancement to continue listening. In this case, this issue might cause potential problems.