diff --git a/arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java b/arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java
index 5adcbf201..462cdd353 100644
--- a/arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java
+++ b/arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java
@@ -59,7 +59,6 @@ public class LibrariesIndexer {
 
   private LibrariesIndex index;
   private final LibraryList installedLibraries = new LibraryList();
-  private final LibraryList installedLibrariesWithDuplicates = new LibraryList();
   private List<File> librariesFolders;
   private final File indexFile;
   private final File stagingFolder;
@@ -113,7 +112,6 @@ public class LibrariesIndexer {
   public void rescanLibraries() {
     // Clear all installed flags
     installedLibraries.clear();
-    installedLibrariesWithDuplicates.clear();
 
     if (index.getLibraries() == null) {
       return;
@@ -180,11 +178,6 @@ public class LibrariesIndexer {
         throw new IOException(lib.getSrcFolder().getAbsolutePath());
       }
       installedLibraries.addOrReplace(lib);
-      if (isSketchbook) {
-        installedLibrariesWithDuplicates.add(lib);
-      } else {
-        installedLibrariesWithDuplicates.addOrReplace(lib);
-      }
       return;
     }
 
@@ -196,11 +189,6 @@ public class LibrariesIndexer {
       throw new IOException(lib.getSrcFolder().getAbsolutePath());
     }
     installedLibraries.addOrReplaceArchAware(lib);
-    if (isSketchbook) {
-      installedLibrariesWithDuplicates.add(lib);
-    } else {
-      installedLibrariesWithDuplicates.addOrReplaceArchAware(lib);
-    }
 
     // Check if we can find the same library in the index
     // and mark it as installed
@@ -229,15 +217,6 @@ public class LibrariesIndexer {
     return new LibraryList(installedLibraries);
   }
 
-  // Same as getInstalledLibraries(), but allow duplicates between
-  // builtin+package libraries and sketchbook installed libraries.
-  // However, do not report duplicates among builtin and packages, to
-  // allow any package to override builtin libraries without being
-  // reported as duplicates.
-  public LibraryList getInstalledLibrariesWithDuplicates() {
-    return installedLibrariesWithDuplicates;
-  }
-
   public File getStagingFolder() {
     return stagingFolder;
   }
diff --git a/arduino-core/src/processing/app/BaseNoGui.java b/arduino-core/src/processing/app/BaseNoGui.java
index 4d6401701..328d57750 100644
--- a/arduino-core/src/processing/app/BaseNoGui.java
+++ b/arduino-core/src/processing/app/BaseNoGui.java
@@ -816,25 +816,6 @@ public class BaseNoGui {
             .format("Unable to list header files in {0}", lib.getSrcFolder()), e);
       }
     }
-    // repeat for ALL libraries, to pick up duplicates not visible normally.
-    // any new libraries found here are NEVER used, but they are added to the
-    // end of already-found headers, to allow Compiler to report them if
-    // the sketch tries to use them.
-    for (UserLibrary lib : librariesIndexer.getInstalledLibrariesWithDuplicates()) {
-      try {
-        String headers[] = headerListFromIncludePath(lib.getSrcFolder());
-        for (String header : headers) {
-          LibraryList list = importToLibraryTable.get(header);
-          if (list != null) {
-            if (!(list.hasLibrary(lib))) {
-              list.addLast(lib);
-              //System.out.println(" duplicate lib: " + lib.getInstalledFolder().getPath());
-            }
-          }
-        }
-        } catch (IOException e) {
-      }
-    }
   }
 
   static public void initParameters(String args[]) throws Exception {