Double sound for incoming mail.

Check your settings in the Counters preferences pane (⌘,). You can
have 4 counters each with each own sound. Maybe you have configured
sounds for more than 1 counter?

Another explanation can be that MailMate plays the “new mail” sound
for each account synchronized. The main reason for this is that it is a
consequence of the internal design of MailMate. (I haven't yet decided
how to change/improve this.)

I didn't understand the square in preference pane as 4 counters. Instead I thought it was where the (1) counter was going to appear on the screen. Now that I get it I have fixed my problem. Thanks again.

Jim