Selenium - Метод выполняется два раза

Делается тест на Selenium 3.141.59, TestNG 7.1.0. для сайта https://cloud.google.com/products/calculator

Периодически, при прогонке теста, осуществляется повторный вызов метода (например, для Operating System нужно выбрать определенный пункт). Сначала выбирает нормально и тест, как бы, должен идти дальше (например нажать на Machine Class), но вместо этого осуществляется повторный клик по Operating System и тест ломается.

Может кто сталкивался?

static ArrayList<String> tab;
public static Double priceOnCalculatorPage;

private final Logger logger = LogManager.getRootLogger();

public PageWithSettings(WebDriver driver) {
    super(driver);
}

@FindBy(xpath = "//input[contains(@ng-model,'quantity')]")
private WebElement numberOfInstances;

@FindBy(xpath = "//label[text()='Operating System / Software']/../md-select")
private WebElement listOperatingSystem;

private String typeOperatingSystem = "//md-option[@value='%s']";

@FindBy(xpath = "//md-select[@placeholder='VM Class']")
private WebElement listMachineClass;

private String typeMachineClass = "//md-select-menu[@style=contains(text(), '')]/descendant::md-option[@value='%s']";

@FindBy(xpath = "//md-select[@placeholder='Instance type']")
private WebElement listMachineType;

private String typeMachineType = "//md-option[@value='CP-COMPUTEENGINE-VMIMAGE-%s']";

@FindBy(xpath = "//*[contains(@ng-model,'GPU')]")
private WebElement addGPU;

@FindBy(xpath = "//md-select[@placeholder='Number of GPUs']")
private WebElement listNumberOfGPU;

private String typeNumberOfGPU = "//div[normalize-space()='%s']/parent::md-option";

@FindBy(xpath = "//md-select[@placeholder='GPU type']")
private WebElement listGPUType;

private String typeGPUType = "//md-option[@value='%s']";

@FindBy(xpath = "//md-select[@placeholder='Local SSD']")
private WebElement listLocalSSD;

private String typeLocalSSD = "//div[normalize-space()='%s GB']/parent::md-option";

@FindBy(xpath = "//md-select[@placeholder='Datacenter location']")
private WebElement listDatacenterLocation;

private String typeDatacenterLocation = "//md-select-menu[@class='md-overflow']/descendant::div[contains(text(), '%s')]/parent::md-option";

@FindBy(xpath = "//md-select[@placeholder='Committed usage']")
private WebElement listCommittedUsage;

private String typeCommittedUsage = "//md-select-menu[contains(@style, 'transform-origin')]//div[text()='%s']/parent::md-option";

@FindBy(xpath = "//button[@aria-label='Add to Estimate']")
private WebElement buttonAddToEstimate;

@FindBy(xpath = "//button[@id='email_quote']")
private WebElement buttonEmailEstimate;

@FindBy(xpath = "//input[@type='email']")
private WebElement buttonInputMail;

@FindBy(xpath = "//button[@aria-label='Send Email']")
private WebElement buttonSendEmail;

public PageWithSettings checkNumberOfInstances(Calculator calculator){

    driver.switchTo().frame(0);
    driver.switchTo().frame("myFrame");
    waitForVisibility(numberOfInstances);
    numberOfInstances.sendKeys(String.valueOf(calculator.getNumberOfInstance()));
    return this;
}

public PageWithSettings checkOperatingSystem(Calculator calculator){
    click(listOperatingSystem);
    clickByCheckOption(typeOperatingSystem, calculator.getOperatingSystem());
    return this;
}

public PageWithSettings checkMachineClass(Calculator calculator){
    click(listMachineClass);
    clickByCheckOption(typeMachineClass, calculator.getMachineClass());
    return this;
}

public PageWithSettings checkMachineType(Calculator calculator){
    click(listMachineType);
    clickByCheckOption(typeMachineType, calculator.getTypeMachineType());
    return this;
}

public PageWithSettings checkAddGPU(Calculator calculator){
    click(addGPU);
    click(listNumberOfGPU);
    clickByCheckOption(typeNumberOfGPU, String.valueOf(calculator.getNumberOfGPU()));
    click(listGPUType);
    clickByCheckOption(typeGPUType, calculator.getTypeGPUType());
    return this;
}

public PageWithSettings checkLocalSSD(Calculator calculator){
    click(listLocalSSD);
    clickByCheckOption(typeLocalSSD, calculator.getLocalSSD());
    return this;
}

public PageWithSettings checkDatacenterLocation(Calculator calculator){
    click(listDatacenterLocation);
    clickByCheckOption(typeDatacenterLocation, calculator.getDatacenterLocation());
    return this;
}

public PageWithSettings checkCommittedUsage(Calculator calculator){
    click(listCommittedUsage);
    clickByCheckOption(typeCommittedUsage, String.valueOf(calculator.getCommittedUsage()));
    return this;
}

public PageWithSettings addToEstimate(){
    click(buttonAddToEstimate);
    return this;
}

public PageWithSettings emailEstimate(){
    click(buttonEmailEstimate);
    waitForVisibility(buttonInputMail);
    logger.info("Create calculator on page with some settings");
    return this;

}

public PageWithSettings createNewTab(){
    ((JavascriptExecutor) driver).executeScript("window.open()");
    tab = new ArrayList<>(driver.getWindowHandles());
    driver.switchTo().window(tab.get(1));
    return this;
}

public PageWithSettings checkInputMail(){
    driver.switchTo().frame(0);
    driver.switchTo().frame("myFrame");
    waitForVisibility(buttonInputMail);
    buttonInputMail.sendKeys(GenerateMailPage.generateMail);
    return this;
}

public PageWithSettings checkSendEmail(){
    click(buttonSendEmail);
    logger.info("The settings of calculator was success send on generate email");
    return this;
}

public void getPriceInCalculator(){
    driver.switchTo().window(tab.get(0));
    driver.switchTo().frame(0);
    driver.switchTo().frame("myFrame");
    WebElement priceCalculator = new WebDriverWait(driver, 10)
            .until(ExpectedConditions.visibilityOfElementLocated(By.xpath("//md-card-content[@id='resultBlock']//div/b[contains(text(),Total)]")));

    String s = priceCalculator
            .getText()
            .replace("1 month","")
            .replaceAll("[^0-9.]", "");

    priceOnCalculatorPage = Double.parseDouble(s);
}



public WebElement waitForVisibility(WebElement element){
    new WebDriverWait(driver, 20)
            .until(ExpectedConditions.visibilityOf(element));
    return element;
}

public void click(WebElement element){
    waitForVisibility(element);
    element.sendKeys(Keys.ENTER);
}

public void clickByCheckOption(String listOfOption, String option){
    WebElement element = new WebDriverWait(driver, 10)
            .until(ExpectedConditions.visibilityOfElementLocated(By.xpath(String.format(listOfOption, option))));
    element.sendKeys(Keys.ENTER);
}