So I thought that I’d install Office 2013 on a production machine in side by side mode. It WAS my understanding that you could install Office 2013 on a machine with Office 2010 and not replace ANY of the existing programs.
I completed the installed and did the following checks:

Two versions of Excel ? Check.

Two versions of Word ? Check.

Two versions of OneNote ? Check.

Two versions of Outlook ? FAIL.
That is disappointing as Outlook 2010 is REALLY one of the things that I wanted to retain. Now it is gone and I honestly can’t remember seeing a message or a warning informing me that it would be replaced. If I had seen a message I probably wouldn’t have continued with the installation.
Not a huge problem BUT still there is the lesson from today. Not replace actually means not replace everything EXCEPT Outlook in Office 2013.
You have been warned.