diff --git a/dispatchkit/bootstrap_stl.hpp b/dispatchkit/bootstrap_stl.hpp
index 0874cbf..e99a70e 100644
--- a/dispatchkit/bootstrap_stl.hpp
+++ b/dispatchkit/bootstrap_stl.hpp
@@ -138,6 +138,11 @@ namespace dispatchkit
       bootstrap_default_constructible<ContainerType>(system, type);
     }
 
+  template<typename ContainerType>
+    void bootstrap_pair_associative_container(Dispatch_Engine &system, const std::string &type)
+    {
+      bootstrap_associative_container<ContainerType>(system, type);
+    }
 
   template<typename ContainerType>
     void bootstrap_unique_associative_container(Dispatch_Engine &system, const std::string &type)
@@ -164,7 +169,8 @@ namespace dispatchkit
       system.register_type<MapType>(type);
       register_function(system, &MapType::operator[], "[]");
       bootstrap_unique_sorted_associative_container<MapType>(system, type);
-    }
+      bootstrap_pair_associative_container<MapType>(system, type);
+     }
 }
 
 #endif
diff --git a/dispatchkit/dispatchkit.hpp b/dispatchkit/dispatchkit.hpp
index f600293..bc3d0a1 100644
--- a/dispatchkit/dispatchkit.hpp
+++ b/dispatchkit/dispatchkit.hpp
@@ -33,17 +33,25 @@ namespace dispatchkit
 
       void register_function(const boost::shared_ptr<Proxy_Function> &f, const std::string &name)
       {
-        m_functions.insert(std::make_pair(name, f));
-      }
+        if (!add_function(f, name))
+        {
+          std::cout << "Unable to add function: " << name 
+            << " another function with the exact signature exists." << std::endl;
+        }
+     }
 
 
       template<typename Function>
         void register_function(const Function &func, const std::string &name)
         {
-          m_functions.insert(std::make_pair(name, boost::shared_ptr<Proxy_Function>(new Proxy_Function_Impl<Function>(func))));
+          if (!add_function(boost::shared_ptr<Proxy_Function>(new Proxy_Function_Impl<Function>(func)), name))
+          {
+            std::cout << "Unable to add function: " << name 
+              << " another function with the exact signature exists." << std::endl;
+          }
         }
 
-
+ 
       template<typename Class>
         void set_object(const std::string &name, const Class &obj)
         {
@@ -146,6 +154,24 @@ namespace dispatchkit
       }
 
     private:
+      bool add_function(const boost::shared_ptr<Proxy_Function> &f, const std::string &t_name)
+      {
+        std::pair<Function_Map::const_iterator, Function_Map::const_iterator> range
+          = m_functions.equal_range(t_name);
+
+        while (range.first != range.second)
+        {
+          if ((*f) == *(range.first->second))
+          {
+            return false;
+          }
+          ++range.first;
+        }
+
+        m_functions.insert(std::make_pair(t_name, f));
+        return true;
+      }
+
       std::deque<Scope> m_scopes;
 
       Function_Map m_functions;
diff --git a/dispatchkit/proxy_functions.hpp b/dispatchkit/proxy_functions.hpp
index 302ad53..ab22311 100644
--- a/dispatchkit/proxy_functions.hpp
+++ b/dispatchkit/proxy_functions.hpp
@@ -102,7 +102,7 @@ namespace dispatchkit
       virtual ~Proxy_Function() {}
       virtual Boxed_Value operator()(const std::vector<Boxed_Value> &params) = 0;
       virtual std::vector<Type_Info> get_param_types() = 0;
-
+      virtual bool operator==(const Proxy_Function &) const = 0;
   };
 
   class Dynamic_Proxy_Function : public Proxy_Function
@@ -113,6 +113,11 @@ namespace dispatchkit
       {
       }
 
+      bool operator==(const Proxy_Function &f) const
+      {
+        return false;
+      }
+
       virtual ~Dynamic_Proxy_Function() {}
 
       virtual Boxed_Value operator()(const std::vector<Boxed_Value> &params)
@@ -146,7 +151,16 @@ namespace dispatchkit
 
       virtual ~Proxy_Function_Impl() {}
 
-
+      virtual bool operator==(const Proxy_Function &t_func) const
+      {
+        try {
+          dynamic_cast<const Proxy_Function_Impl<Func> &>(t_func);
+          return true; 
+        } catch (const std::bad_cast &) {
+          return false;
+        }
+      }
+ 
       virtual Boxed_Value operator()(const std::vector<Boxed_Value> &params)
       {
         return call_func(m_f, params);