I mostly Ubuntu these days, have been for 15 years, and I cannot recall a time installing a package like Freeipa disabled a website installed by other packages. Obviously YMMv and I might have just been lucky.
With freeipa I meant server, not client. Installing is not enough, configuring it into usable state is needed too (i.e. running freeipa-server-install or freeipa-replica-install).
It is possible to run other services of such configured httpd, but you need to be careful. When freeipa wanted mod_nss, you had to use mod_nss, not mod_ssl (though they switched it); when freeipa wants to use gssproxy, you are going to use gssproxy too. These changes can happen during upgrades, and it is up to you to fix everything after such change.
The project doesn't recommend to run anything else with the same server; you are free to try though.
The point was, that with docker or another container system, any such problems are irrelevant, and it allows you to have separate service instances without having to run separate VMs.
