diff --git a/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/JsonHolder.java b/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/JsonHolder.java
index eacd492892a..2e0f97a7e93 100644
--- a/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/JsonHolder.java
+++ b/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/JsonHolder.java
@@ -48,13 +48,14 @@ public class JsonHolder {
             return jsonExceptionObj;
         }
 
-        public void add(TrackFileImportDeviceIdentifier mapping) {
+        public void addDevice(TrackFileImportDeviceIdentifier mapping) {
             String stringRep = mapping.getId().toString();
             jsonUuidObj.add(stringRep);
         }
-
+        
         public void writeJSONString(HttpServletResponse resp) throws IOException {
             resp.setContentType("text/html");
             jsonResponseObj.writeJSONString(resp.getWriter());
         }
+
     }
\ No newline at end of file
diff --git a/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/SensorDataImportServlet.java b/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/SensorDataImportServlet.java
index b54cd9edd57..e62106bc8c9 100644
--- a/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/SensorDataImportServlet.java
+++ b/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/SensorDataImportServlet.java
@@ -4,8 +4,11 @@ import java.io.BufferedInputStream;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Set;
+import java.util.UUID;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -75,10 +78,14 @@ public class SensorDataImportServlet extends AbstractFileUploadServlet {
                 final String filename = fi.getName();
                 try {
                     importerToUse.importFixes(in, new DoubleVectorFixImporter.Callback() {
+                        Set<UUID> knownDevices = new HashSet<>();
                         @Override
                         public void addFixes(Iterable<DoubleVectorFix> fixes, TrackFileImportDeviceIdentifier device) {
                             storeFixes(fixes, device);
-                            jsonResult.add(device);
+                            if(!knownDevices.contains(device.getId())){
+                                knownDevices.add(device.getId());
+                                jsonResult.addDevice(device);
+                            }
                         }
                     }, filename, requestedImporterName, enableDownsampler);
                     logger.log(Level.INFO, "Successfully imported file " + requestedImporterName);
diff --git a/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/TrackFilesImportServlet.java b/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/TrackFilesImportServlet.java
index a34a10f48df..b1389b57c58 100755
--- a/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/TrackFilesImportServlet.java
+++ b/java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/trackfiles/impl/TrackFilesImportServlet.java
@@ -4,9 +4,11 @@ import java.io.BufferedInputStream;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.UUID;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.stream.Collectors;
@@ -109,10 +111,14 @@ public class TrackFilesImportServlet extends AbstractFileUploadServlet {
                 try (BufferedInputStream in = new BufferedInputStream(fileItem.getInputStream())) {
                     try {
                         importer.importFixes(in, new Callback() {
+                            Set<UUID> knownDevices = new HashSet<>();
                             @Override
                             public void addFix(GPSFix fix, TrackFileImportDeviceIdentifier device) {
                                 storeFix(fix, device);
-                                jsonResult.add(device);
+                                if(!knownDevices.contains(device.getId())){
+                                    knownDevices.add(device.getId());
+                                    jsonResult.addDevice(device);
+                                }
                             }
                         }, true, fileName);
                         succeeded = true;