This bug does not affect version 8u25, I reproduced it on 8u40 build b16
steps to reproduce:
1- create a table with at least 2 columns and 1 row
2- Add a changelistener to its selectedItemProperty
3- click on the first cell, at this point selectedItemProperty takes the value of the first row.
3- click on the same row, second cell
At this point selectedItemProperty is changed to null
4- click back on the first cell
At this point the changelistener is fired twice and selectedItemProperty ends up with null

The following is a sample test code:

import javafx.application.Application;
import javafx.beans.property.ReadOnlyObjectWrapper;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableColumn.CellDataFeatures;
import javafx.scene.control.TableView;
import javafx.stage.Stage;
import javafx.util.Callback;

public class ss extends Application {

public static void main(String[] args) {
launch();
}

@Override
public void start(Stage primaryStage) throws Exception {
TableView<Person> table = new TableView<>();
table.setColumnResizePolicy(TableView.CONSTRAINED_RESIZE_POLICY);
table.setTableMenuButtonVisible(true);
TableColumn<Person, String> column = new TableColumn<>("first");
column.setCellValueFactory(new Callback<CellDataFeatures<Person, String>, ObservableValue<String>>() {
public ObservableValue<String> call(CellDataFeatures<Person, String> p) {
return new ReadOnlyObjectWrapper(p.getValue().getFirstName());
}
});
table.getColumns().add(column);
column = new TableColumn<>("last");
column.setCellValueFactory(new Callback<CellDataFeatures<Person, String>, ObservableValue<String>>() {
public ObservableValue<String> call(CellDataFeatures<Person, String> p) {
return new ReadOnlyObjectWrapper(p.getValue().getLastName());
}
});
table.getColumns().add(column);
table.getItems().addAll(new Person("peter", "M."), new Person("john", "doe"));
table.getSelectionModel().selectedItemProperty().addListener(new SelectionListener());
table.getSelectionModel().selectedIndexProperty().addListener(new indexListener());
primaryStage.setScene(new Scene(table));
primaryStage.show();
}
}

class SelectionListener implements ChangeListener<Person> {
@Override
public void changed(ObservableValue<? extends Person> observable, Person oldValue, Person newValue) {
if (newValue == null) {
System.out.println("null selection");
}
else {
System.out.println("item selected");
}
}
}

class indexListener implements ChangeListener<Number> {
@Override
public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) {
if (newValue == null) {
System.out.println("null index");
}
else {
System.out.println(newValue);
}
}
}

class Person {
String first, last;

public Person(String first, String last) {
super();
this.first = first;
this.last = last;
}

public String getFirstName() {
return first;
}

public Object getLastName() {
return last;
}
}