Index: modules/analysis/icu/src/java/org/apache/lucene/collation/ICUCollationKeyFilter.java
===================================================================
--- modules/analysis/icu/src/java/org/apache/lucene/collation/ICUCollationKeyFilter.java	(revision 1075520)
+++ modules/analysis/icu/src/java/org/apache/lucene/collation/ICUCollationKeyFilter.java	(working copy)
@@ -84,7 +84,12 @@
    */
   public ICUCollationKeyFilter(TokenStream input, Collator collator) {
     super(input);
-    this.collator = collator;
+    // clone the collator: see http://userguide.icu-project.org/collation/architecture
+    try {
+      this.collator = (Collator) collator.clone();
+    } catch (CloneNotSupportedException e) {
+      throw new RuntimeException(e);
+    }
   }
 
   @Override
Index: modules/analysis/icu/src/java/org/apache/lucene/collation/tokenattributes/ICUCollatedTermAttributeImpl.java
===================================================================
--- modules/analysis/icu/src/java/org/apache/lucene/collation/tokenattributes/ICUCollatedTermAttributeImpl.java	(revision 1075520)
+++ modules/analysis/icu/src/java/org/apache/lucene/collation/tokenattributes/ICUCollatedTermAttributeImpl.java	(working copy)
@@ -36,7 +36,12 @@
    * @param collator Collation key generator
    */
   public ICUCollatedTermAttributeImpl(Collator collator) {
-    this.collator = collator;
+    // clone the collator: see http://userguide.icu-project.org/collation/architecture
+    try {
+      this.collator = (Collator) collator.clone();
+    } catch (CloneNotSupportedException e) {
+      throw new RuntimeException(e);
+    }
   }
   
   @Override