Last time you did a major update to TntMPD, you had to copy a newer TntMPD into your Applications folder. Since there was an existing TntMPD in your Applications folder, your Mac gave you three options: "Keep Both", "Replace", and "Stop". You probably chose "Keep Both" so it added in your new TntMPD as "TntMPD 2".
To get past this, just open your Applications folder (in Finder). If "TntMPD" exists, delete it. Then rename "TntMPD 2" to "TntMPD".