You can't have CrossEPG and OpenTV "installed" just because CrossEPG is a plugin/extension (i.e. a kind of application) that can be "installed", while OpenTV is a standard EPG data download protocol, not an application itself.
Therefore, CrossEPG can use OpenTV protocol to get EPG data from a broadcaster.
What you are missing is that Black Hole has 2 different preinstalled "applications" that manage EPG Data (indeed there are others too that can be installed): BH EPG and CrossEPG. They are used in different places of BH (i.e. Channel list and Graphical EPG).
Both can use OpenTV to download EPG data.
They can share the EPG database, so it's not necessary to set up both to download the same OpenTv source.