coherence & shared library updating using wlst

I'm trying to update the coherence gar & shared libraries to weblogic server using WLST.

I am able to achieve deployment of the any ear or datatier(.gar) coherence application without any errors using redeploy() command.

redeploy(applicationName , applicationPath , upload="true")

But same command is not useful for updating the shared library & coherence gar application on Portal server. So used the below command to deploy them.

deploy(libName,libPath,targets=targetServers, libraryModule='true',upload='true') //for normal shared library

deploy('MyCohApp', '/myapps/MyCohApp.gar', 'server1',upload='true', specifiedTargetsOnly='true') //for coherence gar deploy

With this I'm able to deploy the shared library or Coherence gar application on Portal server. But problem is it is not updating the libraries. It just deploy it as a new library rather than deploying it as an updated version of the existing shared library.