It depends on what program or script you're using to see who's in the server. Many programmers reasonably assumed that servers would only host on port 10052, and as a result they hard-coded that port number into their code instead of parsing it from the server list. As a result, an attempt to join Zeal Duels, which is hosted on port 10058, may send you to Zeal Alpha, which is hosted on port 10052. JJ2+ now allows you to join servers hosted on ports other than 10052.