I've some trouble in installing the Oracle SQL Developer Data Modeler parallel in 32/64 bit. The default is both versions are installed parallel in the same directory by unzipping the download file. If the 32bit version is started first, it asks for the 32bit JDK and enters this path in the SetJavaHome placed in the file product.conf found in the directory C:\Users\<username>\AppData\Roaming\Oracle SQL Developer Data Modeler\<Version>\. Here the SetJavaHome must be set to C:\Program Files\Java\jdk<java-version>\ instead of C:\Program Files (x86)\Java\jdk<java-version>\.
It takes me some time to find this configuration file, for the way, described in this diskussion leads into thw wrong direction for the actual version