Linux being Linux, nearly anything is (theoretically) possible - providing you have the patience and/or the technical knowhow! :)
Theoretically it shouldn't be too hard, but the devil is always in the detail...
If you are intending on hosting it locally (and/or on your own hardware) I would strongly urge you to consider the (preferred IMO) alternative of installing a hypervisor OS (such as ProxmoxVE) onto the physical machine and then just install them as separate VMs. If that's a possibility I'd strongly encourage you to have a look at this blog post and use the newly created OVZ templates (under PVE v1.9). This will make it a really easy process and will allow you to add extra functionality at any point easily, as well as keeping the appliances completely separate.
Otherwise if you need to have them in the same appliance I would recommend that you start with one appliance and manually install the other onto it (the websites/wikis/forums/mailinglists/etc of the relevant software should detail how that can be done).
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