Hi Mahlon,
I don’t really have enough information to tell you why this activity is being created, but it appears that Method is picking it up as an event that originated in a Google calendar account. The time doesn’t correlate with the previous 2 activities, so I don’t think that it’s a duplicate. Is the activity assigned to you or another user on the account? Perhaps it was added via someone else’s Google calendar.
You can try locating the activity in the audit trail and this may give you some more information to go off of.
I hope this helps.
-Audisho