Having more than one action with the same action id leads to exception raising:
java.lang.Throwable
at com.intellij.openapi.diagnostic.Logger.error(Logger.java:48)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.registerAction(ActionManagerImpl.java:50)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.a(ActionManagerImpl.java:137)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.c(ActionManagerImpl.java:342)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.a(ActionManagerImpl.java:346)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.readExternal(ActionManagerImpl.java:312)
at com.intellij.openapi.components.impl.stores.ComponentStoreImpl.initJdomExternalizable(ComponentStoreImpl.java:9)
at com.intellij.openapi.components.impl.stores.ComponentStoreImpl.initComponent(ComponentStoreImpl.java:11)
at com.intellij.openapi.components.impl.ComponentManagerImpl.a(ComponentManagerImpl.java:83)
at com.intellij.openapi.components.impl.ComponentManagerImpl.access$1100(ComponentManagerImpl.java:49)
at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentConfigComponentAdapter$1.getComponentInstance(ComponentManagerImpl.java:3)
at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentConfigComponentAdapter.getComponentInstance(ComponentManagerImpl.java:1)
at org.picocontainer.defaults.DefaultPicoContainer.getInstance(DefaultPicoContainer.java:395)
at org.picocontainer.defaults.DefaultPicoContainer.getComponentInstance(DefaultPicoContainer.java:375)
at org.picocontainer.alternatives.AbstractDelegatingMutablePicoContainer.getComponentInstance(AbstractDelegatingMutablePicoContainer.java:75)
at com.intellij.openapi.components.impl.ComponentManagerImpl.a(ComponentManagerImpl.java:36)
at com.intellij.openapi.components.impl.ComponentManagerImpl.a(ComponentManagerImpl.java:154)
at com.intellij.openapi.components.impl.ComponentManagerImpl.initComponents(ComponentManagerImpl.java:27)
at com.intellij.openapi.components.impl.stores.ApplicationStoreImpl.loadApplication(ApplicationStoreImpl.java:76)
at com.intellij.openapi.application.impl.ApplicationImpl.load(ApplicationImpl.java:32)
at com.intellij.idea.IdeaApplication.run(IdeaApplication.java:4)
at com.intellij.idea.Main$3.run(Main.java)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
at com.intellij.ide.IdeEventQueue.b(IdeEventQueue.java:97)
at com.intellij.ide.IdeEventQueue.a(IdeEventQueue.java:56)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:123)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
[ 6563] ERROR - nSystem.impl.ActionManagerImpl - action with the ID "Validate HTML" was already registered. Registered action is com.intellij.openapi.actionSystem.ActionStub@1854d1f Plugin: Plugin name here
java.lang.Throwable
at com.intellij.openapi.diagnostic.Logger.error(Logger.java:48)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.registerAction(ActionManagerImpl.java:50)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.a(ActionManagerImpl.java:137)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.c(ActionManagerImpl.java:342)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.a(ActionManagerImpl.java:346)
at com.intellij.openapi.actionSystem.impl.ActionManagerImpl.readExternal(ActionManagerImpl.java:312)
at com.intellij.openapi.components.impl.stores.ComponentStoreImpl.initJdomExternalizable(ComponentStoreImpl.java:9)
at com.intellij.openapi.components.impl.stores.ComponentStoreImpl.initComponent(ComponentStoreImpl.java:11)
at com.intellij.openapi.components.impl.ComponentManagerImpl.a(ComponentManagerImpl.java:83)
at com.intellij.openapi.components.impl.ComponentManagerImpl.access$1100(ComponentManagerImpl.java:49)
at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentConfigComponentAdapter$1.getComponentInstance(ComponentManagerImpl.java:3)
at com.intellij.openapi.components.impl.ComponentManagerImpl$ComponentConfigComponentAdapter.getComponentInstance(ComponentManagerImpl.java:1)
at org.picocontainer.defaults.DefaultPicoContainer.getInstance(DefaultPicoContainer.java:395)
at org.picocontainer.defaults.DefaultPicoContainer.getComponentInstance(DefaultPicoContainer.java:375)
at org.picocontainer.alternatives.AbstractDelegatingMutablePicoContainer.getComponentInstance(AbstractDelegatingMutablePicoContainer.java:75)
at com.intellij.openapi.components.impl.ComponentManagerImpl.a(ComponentManagerImpl.java:36)
at com.intellij.openapi.components.impl.ComponentManagerImpl.a(ComponentManagerImpl.java:154)
at com.intellij.openapi.components.impl.ComponentManagerImpl.initComponents(ComponentManagerImpl.java:27)
at com.intellij.openapi.components.impl.stores.ApplicationStoreImpl.loadApplication(ApplicationStoreImpl.java:76)
at com.intellij.openapi.application.impl.ApplicationImpl.load(ApplicationImpl.java:32)
at com.intellij.idea.IdeaApplication.run(IdeaApplication.java:4)
at com.intellij.idea.Main$3.run(Main.java)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
at com.intellij.ide.IdeEventQueue.b(IdeEventQueue.java:97)
at com.intellij.ide.IdeEventQueue.a(IdeEventQueue.java:56)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:123)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
[ 6579] ERROR - nSystem.impl.ActionManagerImpl - JDK: 1.5.0_10
[ 6579] ERROR - nSystem.impl.ActionManagerImpl - VM: Java HotSpot(TM) Client VM
[ 6579] ERROR - nSystem.impl.ActionManagerImpl - Vendor: Sun Microsystems Inc.
[ 6579] ERROR - nSystem.impl.ActionManagerImpl - OS: Windows XP