Revert chantes after test new repository without installing new packages

I wanted to test the changes that occurred if I installed a new PHP repository on Debian 9.
Before adding the repository I did an apt-get update and an apt-get dist-upgrade, and there were no changes.
So I added the repository, did an "apt-get update" and then an apt-get dist-upgrade --dry-run ", and also a couple of" apt-get install --dry-run package1 package2 ... "
I didn't like the changes it proposed and removed the repository from the list. And then I did "apt-get update" again to refresh the list of packages.
However now, when I do "apt-get -s dist-upgrade" they appear to install a lot of new packages that should not be, since they correspond to when I added the repository.

Do you know how I could leave it as it was before adding the repository, and not try to install packages that I did not try to install / update before?

Thanks