We installed few hot fixes in SIT environment. Due to some issues we removed all the packages from SIT which are deployed recently including the hot fixes to check the root cause of the issue.
Again we imported all the packages once after the issue is resolved. But not able to re-install the hot fixes again. It is throwing a message "This hot fix already exists". My prediction is somewhere the instances of these hot fixes still exists. That is why it is showing the message "This hot fix already exists". If so where those instances are getting saved?
How did you removed the hotfixes from the system? Did you rolled back the changes from the Hotfix manager page?
The rules in the hotfixes are saved to the database and if you commit the changes, then you have to manually delete thoise rules from the database. However, if the Pega is displaying "Hotfix already exists" then you should check if the issues for which you installed the hotfixes persists in the system or not.
If they are not, then you don't need to install the hotfixes again.