Fix duplicate clip with speed change on comma locales.

Related to #261

src/jobs/speedjob.cpp

@@ -61,8 +61,9 @@ void SpeedJob::configureConsumer()
 void SpeedJob::configureProducer()
 {
     if (!qFuzzyCompare(m_speed, 1.0)) {
+        QLocale locale;
         QString resource = m_producer->get("resource");
-        m_producer = std::make_unique<Mlt::Producer>(*m_profile.get(), "timewarp", QStringLiteral("%1:%2").arg(m_speed).arg(resource).toUtf8().constData());
+        m_producer = std::make_unique<Mlt::Producer>(*m_profile.get(), "timewarp", QStringLiteral("%1:%2").arg(locale.toString(m_speed)).arg(resource).toUtf8().constData());
     }
 }