ctools_entity_from_field relationship does not support fields which contain multiple columns referring to same entity type

For example, I have a complex field (field_multiple_nids) that contains two columns, reference_a and reference_b that both contain referenced node IDs. The code in ctools_entity_from_field only supports the first unique-by-entity-type relationship column found:

  // Get the schema information for every field.
  $fields_info = field_info_fields();
  foreach ($fields_info as $field_name => $field) {
    ...
          $foreign_keys = ctools_field_foreign_keys($field_name);
          foreach ($foreign_keys as $key => $info) {
            if (isset($info['table'])) {
              foreach ($entities as $to_entity => $to_entity_info) {
                $from_entity_info = $entities[$from_entity];
                ...

                if (isset($to_entity_info['base table']) && $to_entity_info['base table'] == $info['table'] && array_keys($info['columns'], $to_entity_info['entity keys']['id'])) {
                  $name = $field_name . '-' . $from_entity . '-' . $to_entity;
                  $plugin_id = $parent . ':' . $name;

                  ...

                  // We check for every bundle; this plugin may already have
                  // been created, so don't recreate it.
                  if (!isset($plugins[$plugin_id])) {
                    $plugin = $parent_plugin;
                    $replacements = array(
                      '@to_entity' => $to_entity_info['label'],
                      '@from_entity' => $from_entity_info['label'],
                      '@field_name' => $field_name,
                      '@field_label' => ctools_field_label($field_name),
                    );
                    $plugin['title'] = t('@to_entity from @from_entity (on @from_entity: @field_label [@field_name])', $replacements);
                    $plugin['keyword'] = $to_entity;
                    $plugin['context name'] = $name;
                    $plugin['name'] = $plugin_id;
                    $plugin['description'] = t('Creates a @to_entity context from @from_entity using the @field_name field on @from_entity.', $replacements);
                    $plugin['from entity'] = $from_entity;
                    $plugin['to entity'] = $to_entity;
                    $plugin['field name'] = $field_name;
                    $plugin['join key'] = $key;
                    $plugin['source key'] = current(array_keys($info['columns']));
                    ...

The above code means that the $name for both columns would both be entity_from_field:field_multiple_nids-node-node and the first column wins (since $plugin['source key'] == 'column_a'), and the second column loses, and does not get a relationship handler. But it should.