Hi,
is there anyone who is actually hosting more than one site within one dzones
hosting plan?
In particular i'm interested to know if, after all, i will have two
different and separated domains, with their sub-dir or if the second domain
will be a kind of "slave" of the first one, so that a user look at
www.1stdomain.com/dir/dir... and www.2nddomain.com/dir/dir .

On their FAQ they says:
Q - Can I host more than one site within my account?
A - Absolutely! Each plan includes a certain number of add-on domains. Each
add-on domain may be created in your control panel and will allow you to
have a different page show up for a different domain name. This means you
don't need a separate hosting account for more than one web site. Keep in
mind that you will still only have one control panel to manage the sites. If
you need a separate control panel, you will need another account.

but on their plan-features page i see "Point Additional Domain to Folder"
nr.. that seems not exactely like having a TRUE second domain within one
hosting plan.

About the single control panel, no problem, both sites are mine.

Thanks in advance for attention.

Add-on domains are just redirected urls to a sub-domain. That's not real Multiple Domain Hosting. For the real deal, email and cpanels for all your domains, you need something like WHM/Cpanel. You setup your domains in the WHM and manage aspects of those domains in their CPanels. This is also referred to as a "Reseller account". :)

Thanks Aussie Bob, i was a bit confused about!