Bug 330553 [Import/Export] Importing a project that exists in workspace location merges the contents
(1) Create a project in the default location (2) Export it to an archive (3) Delete it (but don't choose the option to delete from disk) (4) Make some changes in the <workspace root>/<project> directory (4) Import the archive you exported in step 2 This results in files from both the archive and directory. If the directory already has a file thats available in the archive, then it doesn't modify it. Ideally we shouldn't be allowing the import at all.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/wizards/datatransfer/WizardProjectsImportPage.java
archivePathData.widthHint = new PixelConverter(archivePathField).convertWidthInCharsToPixels(25);
		archivePathField.setLayoutData(archivePathData); 
		browseArchivesButton = new Button(projectGroup, SWT.PUSH);
		browseArchivesButton.setText(DataTransferMessages.DataTransfer_browse);
		setButtonLayoutData(browseArchivesButton);
		projectFromDirectoryRadio.setSelection(true);
		archivePathField.setEnabled(false);
		browseArchivesButton.setEnabled(false);
		browseDirectoriesButton.addSelectionListener(new SelectionAdapter() {
			/*
			 * (non-Javadoc)
			 * 
			 * @see org.eclipse.swt.events.SelectionAdapter#widgetS
			 * elected(org.eclipse.swt.events.SelectionEvent)
			 */
			public void widgetSelected(SelectionEvent e) {
				handleLocationDirectoryButtonPressed();
			}
		});
		browseArchivesButton.addSelectionListener(new SelectionAdapter() {
			/*
			 * (non-Javadoc)
			 * 
			 * @see
			 * org.eclipse.swt.events.SelectionAdapter#widgetSelected(org.eclipse
			 * .swt.events.SelectionEvent)
			 */
			public void widgetSelected(SelectionEvent e) {
				handleLocationArchiveButtonPressed();
			}