First, I would recommend a different configuration. Since you're using the same database for each site, but different file roots, that seems to me like it could cause some interesting problems regarding the CMS itself (expecting to find files it has referenced in the database, but depending on the site that's running, it is a completely different set of files).

Kentico supports multiple sites with a single installation. Since you're using one database, that's what I'd do.

To do this, you can set up multiple sites in IIS, but point them each at the same file root. You can still change your IIS settings individually per site (for error pages and so forth).

By the time Kentico receives the request for a web page, it will look at the hostname requested and start the appropriate site.

As far as the import, you need to make sure you uncheck the appropriate items during import that you don't want to be overwritten. Unfortunately, you can't select each individual page, but you can choose whether or not to import documents (all or none), templates, layouts, css style sheets, etc. Anything that remains checked will get overwritten.

I will admit though, creating a new site is a bit of a tricky process when you have a site already in the same database. I'd rather see a "new EMPTY site" option so my existing css/templates/web part containers/etc. don't have a chance to get overwritten, AND those preset items don't get imported either.

I've mentioned this to Kentico and they did say they're considering including an "empty" template in a future version.

Hope this helps,
Elijah

Hello,
I will agree with Elijah, if you want to have multiple sites in one database, it's preferred to use only one instance of Kentico CMS with multiple sites in it.

In your case it seems that you use default name of your masterpage template, which is overwritten during the creating of new corporate site. You can solve it by creating copy of masterpage template with different name for your existing sites and change it appropriately in your sites or simply uncheck importing of page templates during creating of your new site.

Best Regards,
Zbysek Nemec

You are correct. We trashed existing sites 3-4 times before we figured out what was going on.
Kentico export/import when you have multiple sites using the same DB is very fragile and imo poorly designed.
Check out my post that outlines the process we came up with to work around. Search for Global Template Gochas or this link
http://devnet.kentico.com/Special-Pages/Forums-Search-Results.aspx?SearchForum=Global%20Template%20Gochas
Also beware that versions only apply to content and not CSS or template-level changes.
Good luck.