Merging OSM files with OSMOSIS and import to Postgres with OSM2PGSQL

I have a problem merging and then importing two OSM files. I downloaded to distinct .osm-files from cloudmade. They are not sharing any geographical attribute (as the first is the country Monaco, the 2nd is the county Bremen in Germany).

I merged the with OSMOSIS and it gives me an output file.

Then I import it via OSM2PGSQL.

Looking at the dataset using QGIS it either shows me the data of Bremen or Monaco (depending the order in the OSMOSIS merge statement).

Does anyone has a solution for this problem?

Thanks a lot Carsten

EDIT: I imported like described further down. Downloaded Bremen and Monaco planet files and imported them like this:

$osm2pgsql -l --create --database gis --username postgres --prefix planet --slim --cache 2048 /home/katia/Downloads/monaco.osm.bz2 -S /usr/share/osm2pgsql/default.style

$osm2pgsql -l --append --database gis --username postgres --prefix planet --slim --cache 2048 /home/katia/Downloads/bremen_1.osm.bz2 -S /usr/share/osm2pgsql/default.style

The two files seems to be correctly imported into postgis. No duplicates. But trying them visualizing them in OpenJump it displayes only the bremen.osm data. In PGAdmin3 it shows me that the tables do not have any primary key. How do set them correctly?

Thanks