diff --git a/applications/osgconv/CMakeLists.txt b/applications/osgconv/CMakeLists.txt
index cff54cb79..a4d075abd 100644
--- a/applications/osgconv/CMakeLists.txt
+++ b/applications/osgconv/CMakeLists.txt
@@ -3,12 +3,10 @@
 
 SET(TARGET_SRC
     OrientationConverter.cpp 
-    PluginQuery.cpp
     osgconv.cpp
 )
 SET(TARGET_H
     OrientationConverter.h
-    PluginQuery.h
 )
 
 #### end var setup  ###
diff --git a/applications/osgconv/osgconv.cpp b/applications/osgconv/osgconv.cpp
index 6e261cb1b..458cb0838 100644
--- a/applications/osgconv/osgconv.cpp
+++ b/applications/osgconv/osgconv.cpp
@@ -17,6 +17,7 @@
 #include <osgDB/WriteFile>
 #include <osgDB/FileNameUtils>
 #include <osgDB/ReaderWriter>
+#include <osgDB/PluginQuery>
 
 #include <osgUtil/Optimizer>
 #include <osgUtil/Simplifier>
@@ -28,7 +29,6 @@
 #include <iostream>
 
 #include "OrientationConverter.h"
-#include "PluginQuery.h"
 
 typedef std::vector<std::string> FileNameList;
 
diff --git a/applications/osgconv/PluginQuery.h b/include/osgDB/PluginQuery
similarity index 80%
rename from applications/osgconv/PluginQuery.h
rename to include/osgDB/PluginQuery
index ee0e0de43..4e8cfa491 100644
--- a/applications/osgconv/PluginQuery.h
+++ b/include/osgDB/PluginQuery
@@ -12,6 +12,8 @@
 #ifndef PLUGINQUERY_H
 #define PLUGINQUERY_H
 
+#include <osgDB/Export>
+
 #include <list>
 
 namespace osgDB
@@ -19,8 +21,7 @@ namespace osgDB
 
 typedef std::list<std::string> FileNameList;
 
-
-FileNameList listAllAvailablePlugins();
+FileNameList OSGDB_EXPORT listAllAvailablePlugins();
 
 class ReaderWriterInfo : public osg::Referenced
 {
@@ -35,9 +36,9 @@ class ReaderWriterInfo : public osg::Referenced
 
 typedef std::list< osg::ref_ptr<ReaderWriterInfo> > ReaderWriterInfoList;
 
-bool queryPlugin(const std::string& fileName, ReaderWriterInfoList& infoList);
+bool OSGDB_EXPORT queryPlugin(const std::string& fileName, ReaderWriterInfoList& infoList);
 
-bool outputPluginDetails(std::ostream& out, const std::string& fileName);
+bool OSGDB_EXPORT outputPluginDetails(std::ostream& out, const std::string& fileName);
 
 }
 
diff --git a/src/osgDB/CMakeLists.txt b/src/osgDB/CMakeLists.txt
index 8347b1aae..fb4cada1e 100644
--- a/src/osgDB/CMakeLists.txt
+++ b/src/osgDB/CMakeLists.txt
@@ -24,6 +24,7 @@ SET(LIB_PUBLIC_HEADERS
     ${HEADER_PATH}/Input
     ${HEADER_PATH}/Output
     ${HEADER_PATH}/ParameterOutput
+    ${HEADER_PATH}/PluginQuery
     ${HEADER_PATH}/ReaderWriter
     ${HEADER_PATH}/ReadFile
     ${HEADER_PATH}/Registry
@@ -50,8 +51,9 @@ ADD_LIBRARY(${LIB_NAME}
     ImagePager.cpp
     Input.cpp
     Output.cpp
-    ReadFile.cpp
+    PluginQuery.cpp
     ReaderWriter.cpp
+    ReadFile.cpp
     Registry.cpp
     SharedStateManager.cpp
     Version.cpp
diff --git a/applications/osgconv/PluginQuery.cpp b/src/osgDB/PluginQuery.cpp
similarity index 83%
rename from applications/osgconv/PluginQuery.cpp
rename to src/osgDB/PluginQuery.cpp
index fce51bb1c..93133fd8b 100644
--- a/applications/osgconv/PluginQuery.cpp
+++ b/src/osgDB/PluginQuery.cpp
@@ -12,7 +12,7 @@
 #include <osgDB/FileUtils>
 #include <osg/Version>
 
-#include "PluginQuery.h"
+#include <osgDB/PluginQuery>
 
 using namespace osgDB;
 
@@ -43,6 +43,18 @@ FileNameList osgDB::listAllAvailablePlugins()
 
 bool osgDB::queryPlugin(const std::string& fileName, ReaderWriterInfoList& infoList)
 {
+    typedef std::set<const ReaderWriter*> ReaderWriterSet;
+    ReaderWriterSet previouslyLoadedReaderWriters;
+
+    const Registry::ReaderWriterList& rwList = osgDB::Registry::instance()->getReaderWriterList();
+    for(Registry::ReaderWriterList::const_iterator itr = rwList.begin();
+        itr != rwList.end();
+        ++itr)
+    {
+        const ReaderWriter* rw = itr->get();
+        previouslyLoadedReaderWriters.insert(rw);
+    }
+
     if (osgDB::Registry::instance()->loadLibrary(fileName))
     {
         const Registry::ReaderWriterList& rwList = osgDB::Registry::instance()->getReaderWriterList();
@@ -51,14 +63,18 @@ bool osgDB::queryPlugin(const std::string& fileName, ReaderWriterInfoList& infoL
             ++itr)
         {
             const ReaderWriter* rw = itr->get();
-            osg::ref_ptr<ReaderWriterInfo> rwi = new ReaderWriterInfo;
-            rwi->plugin = fileName;
-            rwi->description = rw->className();
-            rwi->protocols = rw->supportedProtocols();
-            rwi->extensions = rw->supportedExtensions();
-            rwi->options = rw->supportedOptions();
             
-            infoList.push_back(rwi.get());
+            if (previouslyLoadedReaderWriters.count(rw)==0)
+            {
+                osg::ref_ptr<ReaderWriterInfo> rwi = new ReaderWriterInfo;
+                rwi->plugin = fileName;
+                rwi->description = rw->className();
+                rwi->protocols = rw->supportedProtocols();
+                rwi->extensions = rw->supportedExtensions();
+                rwi->options = rw->supportedOptions();
+
+                infoList.push_back(rwi.get());
+            }
         }
 
         osgDB::Registry::instance()->closeLibrary(fileName);