On OSX (tested on Windows 7 x64 and works fine there), if a font is loaded twice via Font.loadFont() the second call will return null. The API for Font.loadFont() says a successfully loaded font will be registered with the subsystem but it does not say that a second call to loadFont may not be successful at all and return null. (And as pointed out, on Windows this is not an issue.)

*** Output of below code on OSX ****

Font load 1 is: Font[name=BebasNeue, family=Bebas Neue, style=Regular, size=18.0]
Font load 2 is: null

*** OTF Font used in test code ***
http://www.fontsquirrel.com/fonts/bebas-neue

*** Test code (ensure path to font matches your setup) ****

package testing;

import javafx.application.Application;
import javafx.application.Platform;
import javafx.scene.text.Font;
import javafx.stage.Stage;

    /**
     * Problem class to show the issue of Font.loadFont() on OSX
     */
    public class FXProblem extends Application
    {
        /**
         * {@inheritDoc}
         */
        @Override
        public void start(final Stage stage) throws Exception
        {
     Font f1 = Font.loadFont(FXProblem.class.getResource("/fonts/BebasNeue.otf").toExternalForm(), 18);
     Font f2 = Font.loadFont(FXProblem.class.getResource("/fonts/BebasNeue.otf").toExternalForm(), 18);
     System.out.println("Font load 1 is: " + f1);
     System.out.println("Font load 2 is: " + f2);
    
     Platform.exit();
     System.exit(0);
        }

        /**
         * Main.
         */
        public static void main(final String[] args)
        {
            launch();
        }
    }