diff --git a/metric/prometheus.go b/metric/prometheus.go
index 32d4d81..9a32756 100644
--- a/metric/prometheus.go
+++ b/metric/prometheus.go
@@ -103,6 +103,10 @@ func (pe *prometheusExporter) loop() {
 		case nm := <-pe.registerChan:
 			var nextmetrics map[string]*prometheusMetricDesc
 			if collector != nil {
+				if collector.metrics[nm.key] != nil {
+					break
+				}
+
 				nextmetrics = collector.metrics
 				prometheus.Unregister(collector)
 				nextmetrics[nm.key] = nm