Problem: Click on an actionURL and action is 
successfully completed and page gets displayed on the browser. Click on 
refresh button again the same action gets called and performs the action
 again.
Resolution: set a tag value in liferay-portlet.xml
<action-url-redirect>true</action-url-redirect>
by default the value of this tag is false.
Note: it’s not a substitute to open another jsp page after completing the action.
Resolution: set a tag value in liferay-portlet.xml
<action-url-redirect>true</action-url-redirect>
by default the value of this tag is false.
Note: it’s not a substitute to open another jsp page after completing the action.