What is also surprising is that you are providing a "cp3" file instead of a "c3p".
Do you get this like that out of Construct or did you rename/made the archive in some way ?
The buttons did work for me as well as intended on Chrome on Windows.
If the behavior happens consistently for you on your Mac, consider filling a bug report.
What is your OS, is it up to date, what is the version of Safari you are using (Chrome is actually Safari with Chrome's skin on Mac), is it up to date ?
If not, updating the OS/Safari possibly could help out.
Also to answer your question about the difference between the events in your first image.
In version 1, the code is supposed to work only once, the first time you place your mouse over the Object.
In version 2, you will trigger the event each time you place your mouse over Object and the action in "Trigger once" will be executed only once (but still each time you trigger the top event/place your mouse over Object).
I hope it makes sense/clarifies things a bit.