Hi,
There is no specific documentation instructing users to create 2 portfolios on the same site. If you want to create 2 separate portfolios on 2 pages, you just need to know how to create one complete portfolio, and the second can be followed by the first one. It's important for you to choose a suitable style to apply to each portfolio.
You can refer to our documentation page to have detailed tutorials:
https://www.tzportfolio.com/document.html
If you're confused about something, feel free to let me know.