Symptoms:
When trying to start appspace or appnode, it fails with the following error found in appnode.log .
++++++++++++
2017-03-02 18:17:03.140 INFO  [main] com.tibco.thor.frwk - bwappnode TIBCO ActiveMatrix BusinessWorks version 6.3.5, build V17, 2017-02-02 initialized using logging config /Applications/TIBCO/BW635/bw/6.3/domains/TSFIDomain/appnodes/TSFIAppSpace/TSFIAppNode/logback.xml
2017-03-02 18:17:03.207 INFO  [AppNodeStateNotificationThread] com.tibco.thor.frwk - AppNodeStateNotificationThread started
2017-03-02 18:17:06.757 ERROR [main] com.tibco.thor.frwk - TIBCO-THOR-FRWK-CMN-500001: Failed to install bundle from [/Applications/TIBCO/BW635/bw/6.3/system/shared/com.tibco.ftl_5.0.0.009]
java.lang.Exception: Found a duplicate bundle within the same folder file:/Applications/TIBCO/BW635/bw/6.3/.ftl_5.0.0system/shared/com.tibco.009/
      at com.tibco.bw.thor.management.common.BW6RepoUtil.installFromFolder(BW6RepoUtil.java:505) [com.tibco.bw.thor.management.common_1.4.500.008.jar:na]
      at com.tibco.bw.thor.management.common.BW6RepoUtil.installFromFolder(BW6RepoUtil.java:357) [com.tibco.bw.thor.management.common_1.4.500.008.jar:na]
      at com.tibco.bw.thor.admin.node.commands.StartCommand.installFromSystem(StartCommand.java:1822) [com.tibco.bw.thor.admin.node_1.4.500.012.jar:na]
      at com.tibco.bw.thor.admin.node.commands.StartCommand.install(StartCommand.java:1352) [com.tibco.bw.thor.admin.node_1.4.500.012.jar:na]
      at com.tibco.bw.thor.admin.node.commands.StartCommand.installProduct(StartCommand.java:1392) [com.tibco.bw.thor.admin.node_1.4.500.012.jar:na]
++++++++++++

Cause:
A duplicate bundle is present in the reported directory which causes a conflict between JARs. If there are multiple versions of FTL installed in the same TIBCO_HOME directory where BW is installed, such issues occur.

AppSpace or AppNode failed to start with the error, "java.lang.Exception: Found a duplicate bundle within the same folder file:/Applications/TIBCO/BW635/bw/6.3/.ftl_5.0.0system/shared/com.tibco.009/".

All

Search for the file "tibftl.jar" under your TIBCO_HOME directory. If you find multiple occurrences of tibftl.jar, then remove the oldest dated .jar file along with its parent folder and keep new one. Then restart the appnode or appspace.
Ex. 
The directory /TIBCO_Home/bw/6.x/system/shared/com.tibco.ftl_5.0.0.009 should be removed considering this is old dated jar present in the TIBCO_HOME