TntMPD for Mac = Mac Packaging + TntMPD
When you get TntMPD for Mac, what you're getting is the Mac Packaging (the magic that makes TntMPD run on a Mac), and TntMPD itself.
As newer versions of TntMPD come out, you can upgrade just TntMPD (within the Mac Packaging):
Or you might notice a newer version of the Mac Packaging itself:
It's recommended that you upgrade the "TntMPD for Mac" first, if an update is available. Then, you can update TntMPD (Mac or PC). The recommended update is highlighted with a white background.
Will you lose your database?
You shouldn't lose your database. Your database file should be in your "Document" folder or on your "Desktop". TntMPD is installed in your "Applications" folder. In TntMPD, under the "Help" menu, click "View System Info" to see where your database is located. Or search your hard drive for files with names ending with ".mpddb" (and take note of the the date of when the file last changed).
Even though you should not lose your database, you should still backup your database before doing an upgrade. You should always be backing up your database regularly, not just when doing updates. I'd suggest using a service like Dropbox (www.dropbox.com) and moving your database to your Dropbox folder so that it gets backed up regularly.