ADDITIONAL SYSTEM INFORMATION :
Windows 11
Java 11
JavaFX 17.0.9

A DESCRIPTION OF THE PROBLEM :
Whenever a TableView is collapsed to zero height and then re-expanded, such as when it is inside a TitledPane, the table's cells are duplicated. The old cells are no longer in the table's VirtualFlow, but they still exist (likely a memory leak) and respond to mouse events, which causes unwanted side effects. In our use case, a custom text field is used to display a selection dialog whenever the cell is edited, so this duplicated cell issue leads to multiple dialogs being displayed when a cell is edited. However, the problem can also be seen with stock table cells such as TextFieldTableCell.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the included example and perform the following steps:
1. Edit the 'Number' cell for 'Alpha', changing the value from 1 to 5.
2. Collapse the TitledPane
3. Expand the TitledPane
4. Edit the 'Number' cell for 'Alpha', changing the value from 5 to 6.
5. Collapse the TitledPane
6. Expand the TitledPane
7. Edit the 'Number' cell for 'Alpha', changing the value from 6 to 7.
8. Collapse the TitledPane
9. Expand the TitledPane
10. Edit the 'Number' cell for 'Alpha', changing the value from 7 to 8.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The output of the program should be:

startEdit number: 1
changed number: 5
titledPane collapsed
titledPane expanded
startEdit number: 5
changed number: 6
titledPane collapsed
titledPane expanded
startEdit number: 6
changed number: 7
titledPane collapsed
titledPane expanded
startEdit number: 7
changed number: 8
ACTUAL -
The output of the program actually is:

startEdit number: 1
changed number: 5
titledPane collapsed
titledPane expanded
startEdit number: 5
startEdit number: 5
changed number: 6
titledPane collapsed
titledPane expanded
startEdit number: 5
startEdit number: 6
startEdit number: 6
changed number: 7
titledPane collapsed
titledPane expanded
startEdit number: 6
startEdit number: 6
startEdit number: 7
startEdit number: 7
changed number: 8

You can see here that each time the TitledPane is collapsed and expanded again, additional 'startEdit' events are shown in the output. These additional events come from the duplicated cells.

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.ReadOnlyStringProperty;
import javafx.beans.property.ReadOnlyStringWrapper;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.collections.FXCollections;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TitledPane;
import javafx.scene.control.cell.TextFieldTableCell;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.util.converter.IntegerStringConverter;

import java.util.Arrays;

public class JavaFXSample extends Application
{
    public static void main(String[] args) {
        launch();
    }

    @Override
    public void start(Stage stage)
    {
        StackPane root = new StackPane();
        root.setAlignment(Pos.TOP_CENTER);

        Scene scene = new Scene(root, 250, 250);

        createNodes(root);

        stage.setTitle("JavaFX Sample");
        stage.setScene(scene);
        stage.show();
    }

    private void createNodes(Pane root)
    {
        TableColumn<SimpleTableItem, String> nameTableColumn = new TableColumn<>("Name");
        nameTableColumn.setCellValueFactory(p -> p.getValue().nameProperty());

        TableColumn<SimpleTableItem, Integer> numberTableColumn = new TableColumn<>("Number");
        numberTableColumn.setCellValueFactory(p -> p.getValue().numberProperty().asObject());
        numberTableColumn.setCellFactory(column -> new TestTableCell<>());

        TableView<SimpleTableItem> tableView = new TableView<>(FXCollections.observableArrayList(
                new SimpleTableItem("Alpha", 1),
                new SimpleTableItem("Beta", 2),
                new SimpleTableItem("Gamma", 3),
                new SimpleTableItem("Delta", 4)));
        tableView.getColumns().setAll(Arrays.asList(nameTableColumn, numberTableColumn));
        tableView.setColumnResizePolicy(TableView.CONSTRAINED_RESIZE_POLICY);
        tableView.setEditable(true);

        TitledPane titledPane = new TitledPane("TitledPane", tableView);
        titledPane.expandedProperty().addListener((observable, oldValue, newValue) ->
                System.out.println("titledPane " + (newValue ? "expanded" : "collapsed")));

        root.getChildren().add(titledPane);
    }


    static class TestTableCell<S> extends TextFieldTableCell<S, Integer>
    {
        TestTableCell()
        {
            super(new IntegerStringConverter());
        }

        @Override
        public void startEdit()
        {
            System.out.println("startEdit number: " + getItem());
            super.startEdit();
        }
    }


    private static class SimpleTableItem
    {
        SimpleTableItem(String name, int number)
        {
            this.name.set(name);
            this.number.set(number);

            numberProperty().addListener((observable, oldValue, newValue) ->
                    System.out.println("changed number: " + newValue));
        }

        private final ReadOnlyStringWrapper name = new ReadOnlyStringWrapper(this, "name");
        ReadOnlyStringProperty nameProperty()
        {
            return name.getReadOnlyProperty();
        }

        private final IntegerProperty number = new SimpleIntegerProperty(this, "discrete");
        IntegerProperty numberProperty()
        {
            return number;
        }
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
None found so far.

FREQUENCY : always