Add validator to unique MQTT device topic filter

@@ -63,6 +63,9 @@
             </mat-error>
           </mat-form-field>
         </div>
+        <mat-error *ngIf="mqttDeviceProfileTransportConfigurationFormGroup.get('configuration').hasError('unique')">
+          {{ 'device-profile.mqtt-device-topic-filters-unique' | translate }}
+        </mat-error>
         <div class="tb-hint" innerHTML="{{ 'device-profile.support-level-wildcards' | translate }}"></div>
         <div class="tb-hint" innerHTML="{{ 'device-profile.single-level-wildcards-hint' | translate }}"></div>
         <div class="tb-hint" innerHTML="{{ 'device-profile.multi-level-wildcards-hint' | translate }}"></div>

@@ -51,7 +51,6 @@ export class MqttDeviceProfileTransportConfigurationComponent implements Control
 
   mqttTransportPayloadTypeTranslations = mqttTransportPayloadTypeTranslationMap;
 
-
   mqttDeviceProfileTransportConfigurationFormGroup: FormGroup;
 
   private requiredValue: boolean;
@@ -87,7 +86,7 @@ export class MqttDeviceProfileTransportConfigurationComponent implements Control
         deviceAttributesTopic: [null, [Validators.required, this.validationMQTTTopic()]],
         deviceTelemetryTopic: [null, [Validators.required, this.validationMQTTTopic()]],
         transportPayloadType: [MqttTransportPayloadType.JSON, Validators.required]
-      })
+      }, {validator: this.uniqueDeviceTopicValidator})
     });
     this.mqttDeviceProfileTransportConfigurationFormGroup.valueChanges.subscribe(() => {
       this.updateModel();
@@ -147,4 +146,14 @@ export class MqttDeviceProfileTransportConfigurationComponent implements Control
       return null;
     };
   }
+
+  private uniqueDeviceTopicValidator(control: FormGroup): { [key: string]: boolean } | null {
+    if (control.value) {
+      const formValue = control.value as MqttDeviceProfileTransportConfiguration;
+      if (formValue.deviceAttributesTopic === formValue.deviceTelemetryTopic) {
+        return {unique: true};
+      }
+    }
+    return null;
+  }
 }

@@ -885,6 +885,7 @@
         "no-device-profiles-found": "No device profiles found.",
         "create-new-device-profile": "Create a new one!",
         "mqtt-device-topic-filters": "MQTT device topic filters",
+        "mqtt-device-topic-filters-unique": "MQTT device topic filters need to be unique.",
         "mqtt-device-payload-type": "MQTT device payload",
         "mqtt-device-payload-type-json": "JSON",
         "mqtt-device-payload-type-proto": "Protobuf",