Forgive me, Jedi Master!
I disputed you. I didn't believe you could create more than SSISDB on a single operating system, BECAUSE if you look at the Feature Selection step of installation, as seen here http://www.e-squillace.com/tech/screenshotgallery/SQL/SQL2012/SQL2012_RTM_Install_Steps_files/Step9b-FeatureSelection-SQLFeatures.png, [SUPPOSEDLY] you can only install Integration Services once per operating system.
So, I had to try out the claim that you could install SSIS on more than one instance per operating system. Of course, the Jedi Master was correct. So, Microsoft, a bit of clarification on the installation screen might help.
Also, take a look at this person's hard work:
Scroll down to this section, "SSISDB ERD – A Journey to DB deployment automation" to see the reverse engineered SSISDB 2012!