How else would deposit #1 find its way into my coinbase account?

Still didn't get it after all of our previous replies?
Okay, I'll break it down in a list:

First open a blockexplorer where 12ngg3CB9VDvkbFDx7JKY92i9kYgDmiEaj's history was listed: here Open in a new Tab
Secondly, from the bottom of the page, transaction afc314f97ab2e02076c4ceba0c2d8493b840b23570b97b2a60fcf5cf57fca9ae is your 1st tx which have inputs from Kraken's addresses to different outputs including 0.09481172 BTC to 12ngg3CB9VDvkbFDx7JKY92i9kYgDmiEaj.
But this tx wasn't credited by coinbase since it isn't their address.
Next, transaction 17fa98a77b8ce4dc91bd9569f4663687922344f223b9979dbb54a31996b11beb the 0.094BTC was quickly sent by the user or malware program to 36ii5gNkZw2vAZ8TVk9dYXtVVbJxk68hiE which belongs to your coinbase account (we can confirm this by looking at the image you've provided)
And this is why the first transaction made it through your coinbase account.

The Second transaction's funds however, is still being held by 12ngg3CB9VDvkbFDx7JKY92i9kYgDmiEaj: f1c52f3edd8fcb8277013b7654bcba48a1c3559bddd6ff305a95491210d6fde0