Test case to reproduce ogr2ogr error loading feature types with no geometry into PostgreSQL 9.1 / PostGIS 1.5. Sample data has been munged to avoid copyright issues.

a.gml

<?xml version="1.0"?>
<FeatureCollection osgb="http://www.ordnancesurvey.co.uk/xml/namespaces/osgb" gml="http://www.opengis.net/gml" fid="GDS-1389940-6811" xsi="http://www.w3.org/2001/XMLSchema-instance" xlink="http://www.w3.org/1999/xlink" schemaLocation="http://www.ordnancesurvey.co.uk/xml/namespaces/osgb http://www.ordnancesurvey.co.uk/xml/schema/v7/OSDNFFeatures.xsd">
    <description>Ordnance Survey, (c) Crown Copyright. All rights reserved, 2013-10-28</description>
    <roadMember>
        <Road fid="osgbfoo">
            <version>5</version>
            <versionDate>2006-02-06</versionDate>
            <theme>Road Network</theme>
            <changeHistory>
                <changeDate>2003-03-13</changeDate>
                <reasonForChange>New</reasonForChange>
            </changeHistory>
            <changeHistory>
                <changeDate>2004-11-11</changeDate>
                <reasonForChange>Modified</reasonForChange>
            </changeHistory>
            <changeHistory>
                <changeDate>2005-09-29</changeDate>
                <reasonForChange>Modified</reasonForChange>
            </changeHistory>
            <changeHistory>
                <changeDate>2005-12-13</changeDate>
                <reasonForChange>Modified</reasonForChange>
            </changeHistory>
            <descriptiveGroup>Named Road</descriptiveGroup>
            <roadName>A LANE</roadName>
            <networkMember href="#osgbbar">
                <networkMember_ref>osgbbar</networkMember_ref>
            </networkMember>
            <networkMember href="#osgbcar">
                <networkMember_ref>osgbcar</networkMember_ref>
            </networkMember>
        </Road>
    </roadMember>
</FeatureCollection>

b.gml

<?xml version="1.0"?>
<FeatureCollection osgb="http://www.ordnancesurvey.co.uk/xml/namespaces/osgb" gml="http://www.opengis.net/gml" fid="GDS-1389940-6811" xsi="http://www.w3.org/2001/XMLSchema-instance" xlink="http://www.w3.org/1999/xlink" schemaLocation="http://www.ordnancesurvey.co.uk/xml/namespaces/osgb http://www.ordnancesurvey.co.uk/xml/schema/v7/OSDNFFeatures.xsd">
    <description>Ordnance Survey, (c) Crown Copyright. All rights reserved, 2013-10-28</description>
    <roadMember>
        <Road fid="osgblar">
            <version>2</version>
            <versionDate>2005-09-12</versionDate>
            <theme>Road Network</theme>
            <changeHistory>
                <changeDate>2004-10-08</changeDate>
                <reasonForChange>New</reasonForChange>
            </changeHistory>
            <descriptiveGroup>Named Road</descriptiveGroup>
            <roadName>A CLOSE</roadName>
            <networkMember href="#osgbde">
                <networkMember_ref>osgbde</networkMember_ref>
            </networkMember>
        </Road>
    </roadMember>
</FeatureCollection>

ogr2ogr_gml_to_pg_no_geom_error.sh

# Load into a fresh schema which does not already contain a road table

# Load the first file
ogr2ogr -append -skipfailures -f PostgreSQL PG:"dbname=loader active_schema=osmm_itn host=localhost user=username password=password" a.gml

# Load the second file
ogr2ogr -append -skipfailures -f PostgreSQL PG:"dbname=loader active_schema=osmm_itn host=localhost user=username password=password" b.gml

# Error output
ERROR 1: Layer road already exists, CreateLayer failed.
Use the layer creation option OVERWRITE=YES to replace it.