Does Selenium WebDriver Support Multiple Instances of the WebDriver Sub-classes

Each instance of an HtmlUnitDriver, ChromeDriver and FirefoxDriver is completely independent of every other instance. In the case of Firefox and chrome, each instance has its own anonymous profile it uses. There is a limitation with InternetExplorerDriver, at a time it could have only single instance at one time. You can use RemoteWebDriver and virtual machines if you want to create more than one instance of InternetExplorerDriver.