diff --git a/owlps-positioning/src/positioning.cc b/owlps-positioning/src/positioning.cc
index f717a4c..4cdeda0 100644
--- a/owlps-positioning/src/positioning.cc
+++ b/owlps-positioning/src/positioning.cc
@@ -12,8 +12,10 @@
 #include <owlps.h>
 
 #include <iostream>
+#include <boost/tr1/unordered_set.hpp>
 
 using namespace std ;
+using std::tr1::unordered_set ;
 
 
 
@@ -49,36 +51,65 @@ void Positioning::initialise_algorithms()
   const vector<string> &algo_names =
     Configuration::string_vector_value("positioning.algorithm") ;
 
+  // We will store the names of the stored algorithms in a set, to
+  // avoid multiple occurrences of the same algorithm:
+  unordered_set<string> stored_algos ;
+
   for (vector<string>::const_iterator i = algo_names.begin() ;
        i != algo_names.end() ; ++i)
     {
       if (*i == "Real")
-        /* In order to compute the errors of the other algorithms,
-         * Real must be the first for each request, so we add it at
-         * the begining.
-         */
-        algorithms.insert(algorithms.begin(), new RealPosition) ;
+        {
+          pair<unordered_set<string>::iterator, bool> stored =
+            stored_algos.insert("Real") ;
+          if (stored.second) // Check if there was no previous instance
+            algorithms.insert(algorithms.begin(), new RealPosition) ;
+          /* Note: in order to compute the errors of the other
+           * algorithms, Real must be the first for each request,
+           * so we add it at the begining. */
+        }
 
       else if (*i == "FBCM")
         {
-          // Generate the Friis indexes only if the autocalibration is
-          // not activated (if it is, Friis indexes will be regenerated
-          // each time FBCM wants to computes a position)
-          if (! Configuration::
-              bool_value("positioning.generate-reference-points"))
-            Stock::update_all_friis_indexes() ;
-          algorithms.push_back(new FBCM) ;
+          pair<unordered_set<string>::iterator, bool> stored =
+            stored_algos.insert("FBCM") ;
+          if (stored.second) // Check if there was no previous instance
+            {
+              /* Generate the Friis indexes only if the autocalibration
+               * is not activated (if it is, Friis indexes will be
+               * regenerated each time FBCM wants to computes a position)
+               */
+              if (! Configuration::
+                  bool_value("positioning.generate-reference-points"))
+                Stock::update_all_friis_indexes() ;
+              algorithms.push_back(new FBCM) ;
+            }
         }
 
       else if (*i == "FRBHMBasic")
-        //TODO: Pre-compute all per-ReferencePoint friis indexes?
-        algorithms.push_back(new FRBHMBasic) ;
+        {
+          pair<unordered_set<string>::iterator, bool> stored =
+            stored_algos.insert("FRBHMBasic") ;
+          if (stored.second) // Check if there was no previous instance
+            algorithms.push_back(new FRBHMBasic) ;
+          // TODO: Pre-compute all per-ReferencePoint friis indexes?
+        }
 
       else if (*i == "InterlinkNetworks")
-        algorithms.push_back(new InterlinkNetworks) ;
+        {
+          pair<unordered_set<string>::iterator, bool> stored =
+            stored_algos.insert("InterlinkNetworks") ;
+          if (stored.second) // Check if there was no previous instance
+            algorithms.push_back(new InterlinkNetworks) ;
+        }
 
       else if (*i == "RADAR")
-        algorithms.push_back(new RADAR) ;
+        {
+          pair<unordered_set<string>::iterator, bool> stored =
+            stored_algos.insert("RADAR") ;
+          if (stored.second) // Check if there was no previous instance
+            algorithms.push_back(new RADAR) ;
+        }
 
       else
         throw bad_configuration(