diff --git a/plugins/ports/functions.go b/plugins/ports/functions.go
index b4ddd52fd..938cba1de 100644
--- a/plugins/ports/functions.go
+++ b/plugins/ports/functions.go
@@ -353,7 +353,7 @@ func parsePortMapString(stringPortMap string) ([]PortMap, error) {
 		})
 	}
 
-	return uniquePortMaps(portMaps), nil
+	return portMaps, nil
 }
 
 // removePortMaps removes specific port mappings from an app
@@ -406,8 +406,12 @@ func reusesSchemeHostPort(portMaps []PortMap) error {
 
 // setPortMaps sets the port maps for an app
 func setPortMaps(appName string, portMaps []PortMap) error {
+	if err := reusesSchemeHostPort(portMaps); err != nil {
+		return fmt.Errorf("Error validating port mappings: %s", err)
+	}
+
 	var value []string
-	for _, portMap := range uniquePortMaps(portMaps) {
+	for _, portMap := range portMaps {
 		if portMap.AllowsPersistence() {
 			continue
 		}
diff --git a/tests/unit/ports.bats b/tests/unit/ports.bats
index e7d451ee5..6eed8f0fe 100644
--- a/tests/unit/ports.bats
+++ b/tests/unit/ports.bats
@@ -59,7 +59,7 @@ teardown() {
   echo "status: $status"
   assert_failure
 
-  run /bin/bash -c "dokku ports:add $TEST_APP http:12345:5003 http:12345:5004"
+  run /bin/bash -c "dokku ports:add $TEST_APP http:12345:5002 http:12345:5004"
   echo "output: $output"
   echo "status: $status"
   assert_failure