diff --git a/ksgrd/SensorAgent.h b/ksgrd/SensorAgent.h
--- a/ksgrd/SensorAgent.h
+++ b/ksgrd/SensorAgent.h
@@ -27,7 +27,7 @@
 #include <QObject>
 #include <QQueue>
 #include <QPointer>
-
+#include <QSet>
 
 class QString;
 
@@ -107,6 +107,7 @@
 
     bool mDaemonOnLine;
     QString mHostName;
+    QSet<SensorRequest> mUnderwayRequests;
 };
 
 /**
@@ -127,6 +128,14 @@
     void setId( int );
     int id();
 
+  friend uint qHash(const SensorRequest& sr, uint seed=0) {
+    return qHash(qMakePair(sr.mRequest, qMakePair(sr.mClient, sr.mId)), seed);
+  }
+  friend bool operator==(const SensorRequest& a, const SensorRequest& b) {
+    return a.mRequest == b.mRequest &&
+      a.mClient == b.mClient &&
+      a.mId == b.mId;
+  }
   private:
     QString mRequest;
     SensorClient *mClient = nullptr;
diff --git a/ksgrd/SensorAgent.cpp b/ksgrd/SensorAgent.cpp
--- a/ksgrd/SensorAgent.cpp
+++ b/ksgrd/SensorAgent.cpp
@@ -56,18 +56,10 @@
 void SensorAgent::sendRequest( const QString &req, SensorClient *client, int id )
 {
   SensorRequest *sensorreq = nullptr;
-  for(int i =0, total = mInputFIFO.size(); i < total; ++i) {
-    sensorreq = mInputFIFO.at(i);
-    if(id == sensorreq->id() && client == sensorreq->client() && req == sensorreq->request()) {
-      executeCommand();
-      return; //don't bother to resend the same request if we already have it in our queue to send
-    }
-  }
-  for(int i =0, total = mProcessingFIFO.size(); i < total; ++i) {
-    sensorreq = mProcessingFIFO.at(i);
-    if(id == sensorreq->id() && client == sensorreq->client() && req == sensorreq->request())
-      return; //don't bother to resend the same request if we have already sent the request to client and just waiting for an answer
-  }
+  SensorRequest nRequest { req, client, id };
+  if (mUnderwayRequests.contains(nRequest))
+    return;
+  mUnderwayRequests.insert(nRequest);
 
   /* The request is registered with the FIFO so that the answer can be
    * routed back to the requesting client. */
@@ -168,6 +160,7 @@
 	}
 		
 	SensorRequest *req = mProcessingFIFO.dequeue();
+	mUnderwayRequests.remove(*req);
 	// we are now responsible for the memory of req - we must delete it!
 	if ( !req->client() ) {
 		/* The client has disappeared before receiving the answer