diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/datalayer/checks/OrientationTableDuplicatesCheck.java b/src/main/java/ch/ethz/seb/sebserver/webservice/datalayer/checks/OrientationTableDuplicatesCheck.java
index 0a391e44..9a61513b 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/datalayer/checks/OrientationTableDuplicatesCheck.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/datalayer/checks/OrientationTableDuplicatesCheck.java
@@ -11,7 +11,9 @@ package ch.ethz.seb.sebserver.webservice.datalayer.checks;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.stream.Collectors;
 
+import org.mybatis.dynamic.sql.SqlBuilder;
 import org.springframework.context.annotation.Lazy;
 import org.springframework.stereotype.Component;
 import org.springframework.transaction.annotation.Transactional;
@@ -19,6 +21,7 @@ import org.springframework.transaction.annotation.Transactional;
 import ch.ethz.seb.sebserver.gbl.profile.WebServiceProfile;
 import ch.ethz.seb.sebserver.gbl.util.Result;
 import ch.ethz.seb.sebserver.webservice.DBIntegrityCheck;
+import ch.ethz.seb.sebserver.webservice.datalayer.batis.mapper.OrientationRecordDynamicSqlSupport;
 import ch.ethz.seb.sebserver.webservice.datalayer.batis.mapper.OrientationRecordMapper;
 import ch.ethz.seb.sebserver.webservice.datalayer.batis.model.OrientationRecord;
 
@@ -68,7 +71,12 @@ public class OrientationTableDuplicatesCheck implements DBIntegrityCheck {
             }
 
             if (tryFix) {
-                toDelete
+                final List<Long> checkedToDelete = toDelete
+                        .stream()
+                        .filter(this::doubleCheck)
+                        .collect(Collectors.toList());
+
+                checkedToDelete
                         .stream()
                         .forEach(this.orientationRecordMapper::deleteByPrimaryKey);
                 return "Fixed duplicates by deletion: " + toDelete;
@@ -79,6 +87,24 @@ public class OrientationTableDuplicatesCheck implements DBIntegrityCheck {
         });
     }
 
+    private boolean doubleCheck(final Long id) {
+        try {
+            final OrientationRecord selectByPrimaryKey = this.orientationRecordMapper.selectByPrimaryKey(id);
+            final Long count = this.orientationRecordMapper.countByExample()
+                    .where(
+                            OrientationRecordDynamicSqlSupport.configAttributeId,
+                            SqlBuilder.isEqualTo(selectByPrimaryKey.getConfigAttributeId()))
+                    .and(
+                            OrientationRecordDynamicSqlSupport.templateId,
+                            SqlBuilder.isEqualTo(selectByPrimaryKey.getTemplateId()))
+                    .build()
+                    .execute();
+            return count != null && count.longValue() > 1;
+        } catch (final Exception e) {
+            return false;
+        }
+    }
+
     @Override
     public String toString() {
         final StringBuilder builder = new StringBuilder();
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/indicator/PingIntervalClientIndicator.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/indicator/PingIntervalClientIndicator.java
index 4461963a..7b2c80b5 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/indicator/PingIntervalClientIndicator.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/indicator/PingIntervalClientIndicator.java
@@ -87,7 +87,8 @@ public final class PingIntervalClientIndicator extends AbstractPingIndicator {
             this.lastUpdate = this.distributedIndicatorValueService.lastUpdate();
         }
 
-        return currentTimeMillis - value;
+        final double res = currentTimeMillis - value;
+        return res >= 0.0D ? res : 0.0D;
     }
 
     @Override
diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAPI_V1_Controller.java b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAPI_V1_Controller.java
index 04918acb..a6a042b1 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAPI_V1_Controller.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/weblayer/api/ExamAPI_V1_Controller.java
@@ -286,23 +286,23 @@ public class ExamAPI_V1_Controller {
     public void ping(final HttpServletRequest request, final HttpServletResponse response) {
 
         final String connectionToken = request.getHeader(API.EXAM_API_SEB_CONNECTION_TOKEN);
-        final String timeStampString = request.getParameter(API.EXAM_API_PING_TIMESTAMP);
+        //final String timeStampString = request.getParameter(API.EXAM_API_PING_TIMESTAMP);
         final String pingNumString = request.getParameter(API.EXAM_API_PING_NUMBER);
         final String instructionConfirm = request.getParameter(API.EXAM_API_PING_INSTRUCTION_CONFIRM);
 
-        long pingTime;
-        try {
-            pingTime = Long.parseLong(timeStampString);
-        } catch (final Exception e) {
-            log.error("Invalid ping request: {}", connectionToken);
-            response.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());
-            return;
-        }
+//        long pingTime;
+//        try {
+//            pingTime = Long.parseLong(timeStampString);
+//        } catch (final Exception e) {
+//            log.error("Invalid ping request: {}", connectionToken);
+//            response.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());
+//            return;
+//        }
 
         final String instruction = this.sebClientConnectionService
                 .notifyPing(
                         connectionToken,
-                        pingTime,
+                        Utils.getMillisecondsNow(),
                         pingNumString != null ? Integer.parseInt(pingNumString) : -1,
                         instructionConfirm);