Unfortunately, there's no logging of this information that's visible via the main interface. While you could probably get this information from a custom plugin or digging through the logs, I'd suggest that the easiest way is to include yourself in the sharing. That way, you'll get an email about the share action. In that email it tells the recipient who else received that notification. See below for how it looks for me:
Most of us don’t need much convincing that stakeholder management is important. It just makes sense that keeping everyone in-the-know on projects and assigning clearly defined roles is key to having ...
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