Duplicate label in a popup

Hi, I have a problem with a popup in vaadin. I use the next code for generate my popup:

public void buttonClick(ClickEvent event) {
				popup.setClosable(true);
				popup.setResizable(false);
				
				
				Label informacionPassword=new Label("Mínimo 8 carácteres alfanuméricos y una mayúscula.\t");
				
		        popup.setContent(subContent);
		        subContent.addComponent(informacionPassword);
		        popup.center();
		        UI.getCurrent().addWindow(popup);		        
			}
		});

The problem is that when I click twice on the button for open the popup the content of the label appears twice. I try to clean the content of the popup before open it.

popup.setContent(subContent);

I recommend to insantiate your subContent also in that ClickEvent. Or even better, refactor the whole creation of the popup in its own method or class.