do not duplicate existing sdks in create virtualenv

python/ide/src/com/jetbrains/python/configuration/PythonSdkDetailsDialog.java

@@ -89,7 +89,6 @@ public class PythonSdkDetailsDialog extends DialogWrapper {
 
   @Override
   protected void dispose() {
-    myInterpreterList.disposeModel();
     myProjectSdksModel.removeListener(myListener);
     super.dispose();
   }

python/src/com/jetbrains/python/sdk/PythonSdkDetailsStep.java

@@ -154,7 +154,7 @@ public class PythonSdkDetailsStep extends BaseListPopupStep<String> {
     final List<PythonSdkFlavor> flavors = PythonSdkFlavor.getApplicableFlavors(false);
     for (PythonSdkFlavor flavor : flavors) {
       final Collection<String> strings = flavor.suggestHomePaths();
-      for (String string : strings) {
+      for (String string : SdkConfigurationUtil.filterExistingPaths(PythonSdkType.getInstance(), strings, myExistingSdks)) {
         allSdks.add(new PyDetectedSdk(string));
       }
     }