opening multiple libraries in photos 4.0

What I did is turned photos off, then held the option key and opened photos and then chose my library.

When you open an Aperture Library this way, Photos will create a new Photos Library from your Aperture library and not merge it with your current Photos Library. Have you tried to switch back to your original Photos Library? Has the original Library really been modified and merged with the Aperture library?

That is very surprising. How have you been opening the Aperture Library? When I ctrl-click an Aperture Library and select "Open with Photos", the Photos.app will create a new Photos Library from The Aperture Library.

Did you perhaps import the Aperture Library to Photos instead of opening it in Photos? What exactly did you do?

Do I somehow need to delete my iCloud library before I restore my old library? I'm just wondering if you might know the answer.

If your library is syncing with iCloud you need indeed to delete the photos from iCloud as well or they will just sync back.

If you imported the photos from folder, you should find all photos you imported accidentally in one place in the "Imports" album - the most recently imported photos should be together at the bottom of this album. I would delete all photos from there, that you do not want to keep in your library. If you use Photos to delete the photos, they will also be removed from iCLoud and all other synced devices.