For a domain or workgroup to be seen on a given subnet (really, broadcast domain of a LAN, not necessarily a single IPv4 subnet per se), it must have at least one member on that subnet, and that member (or "one of those members" if there are more than one) must act as a master browser for that domain or workgroup on that subnet.

So you should expect to see one master browser for each domain or workgroup that has members present on that subnet. So if you have a subnet with 4 machines and each is a member of a different domain or workgroup, then each will be the master browser for its own domain/workgroup on that subnet, so you will have 4 master browsers on that subnet.

I don't know the internals of the exact registrations well enough to tell you how that maps to registrations of the group name \x01\x02__MSBROWSE__\x02\x01.

I don't get it too but... try this. It works!

    String source = "smb://SERVER/PATH/FILE";
    NtlmPasswordAuthentication auth = new NtlmPasswordAuthentication(null, "USERNAME", "PASSWORD");
    SmbFile sourceFile = new SmbFile(source, auth);
    String destination = "LOCAL_PATH_TO_FILE";

    byte[] buffer;
    int length;

    try {
        FileOutputStream fileOutputStream = new FileOutputStream(destination);
        InputStream fileInputStream = sourceFile.getInputStream();
        try {
            buffer = new byte[16 * 1024 * 1024];
            while ((length = fileInputStream.read(buffer)) > 0) {
                fileOutputStream.write(buffer, 0, length);
            }
        } finally {
            fileInputStream.close();
            fileOutputStream.close();
        }
    } catch (SmbException e) {
        // Error handling.    
    } catch (FileNotFoundException e) {
        // Error handling.
    } catch (IOException e) {
        // Error handling.
    }

Credits go to this question and answer: How to copy file from smb share to local drive using jcifs in Java?

It only means it is the Master Browser for the group in question. Groups and subnets are not identical: you may have several distinct groups on a given subnet, which is one possible reason why you may find several Master Browsers on the same subnet.

Actually, if a certain groupd does not have a Master Browser on a given subnet, then the groupd will not be visible.

If interested, you can find a longer discussion on a Microsoft site, here.

I believe you may relax.