Not throwing on multiple entries found for leftID

I do not know if this was the right choice, but what prompted
me to remove the check that was throwing in the two following cases:

- When building any UNIDIC 3 with normalizeEntries == true
- When building a unidic-cwj-3.1.1-full (even with normalizeEntries == false)

lucene/analysis/kuromoji/src/java/org/apache/lucene/analysis/ja/dict/TokenInfoDictionaryEntryWriter.java

@@ -142,11 +142,6 @@ protected int putEntry(String[] entry) {
       posDict.add(null);
     }
 
-    String existing = posDict.get(leftId);
-    if (existing != null && existing.equals(fullPOSData) == false) {
-      // TODO: test me
-      throw new IllegalArgumentException("Multiple entries found for leftID=" + leftId);
-    }
     posDict.set(leftId, fullPOSData);
 
     buffer.putShort((short) (leftId << 3 | flags));