In fact there was already a method "ensureUniqueSeriesName" doing almost the same thing (for example when you were loading several time the same image, you got seriename_1,seriename_2, seriename_3), so I just try this very quickly and it seems to work:

    if (isPartialImport)
   {
        QString seriesName = medMetaDataKeys::SeriesDescription.getFirstValue(dtkData).simplified();
        QString newSeriesDescription = ensureUniqueSeriesName(seriesName);
        dtkData->setMetaData(medMetaDataKeys::SeriesDescription.key(), QStringList()<< newSeriesDescription );
    }