Two different nominatim setup on same server

I assume you run the stable version 2.5.0 or 2.5.1 (http://www.nominatim.org/)

• install the second Nominatim in a new (different) directory. See https://wiki.openstreetmap.org/wiki/Nominatim/Installation

• In the step "Customization of the Installation" use different settings: In settings/local.php change CONST_Database_DSN to use different database, for example pgsql://postgres@localhost:5432/nominatim_2 (see settings.php for the default value).

• When you start the data import from the new directory it will read the settings.php and local.php file and write to that database. If the database name already exists it will NOT overwrite it (that's good).

• You need two configurations in your Apache configuration. It should be enough to copy the existing block and change the URL path and installation directory.

• In the local.php set the CONST_Website_BaseURL to the URL you set in the Apache configuration.

If that doesn't work report problems to https://github.com/twain47/Nominatim/issues

P.S. it's possible to merge two countries and use one installation, that might be easier https://help.openstreetmap.org/questions/48843/merging-two-or-more-geographical-areas-to-import-two-or-more-osm-files-in-nominatim