6567 TagName serialization fix

bindings/java/src/org/sleuthkit/datamodel/TaggingManager.java

@@ -183,7 +183,7 @@ public void deleteTagSet(TagSet tagSet) throws TskCoreException {
 	 * @throws TskCoreException If there is an error querying the case database.
 	 */
 	public TagSet getTagSetForTagName(TagName tagName) throws TskCoreException {
-		if (tagName == null || tagName == null) {
+		if (tagName == null) {
 			throw new IllegalArgumentException("Null tagName argument");
 		}