Slabnose sent me his configuration and I've been running some fairly extensive tests. This is definitely an issue. The issue where sounds get played twice was not known - I've identified this and fixed it. The situation that DaveBullets noted will be fixed in version 2.4 simply by the fact that the sounds/events code is being rewritten entirely.
The issue where a sound sometimes doesn't play was a known issue. Usually this can be attributed to slower computers, or something else happening at or just before a sound event is supposed to play. For example, a sound event that should play at 60 seconds left, and the operator busts a player out at 61 seconds left. Sometimes the processing of the bust-outs and/or the updates to the screen may delay the check for sound events at 60 seconds so that it doesn't happen until 59 seconds (or later), and thus the sound event gets missed.
After doing some research I found out that this was happening a lot more often than I thought, and not just when "something else" happens. If you don't have a lot of sound events configured, you're unlikely to notice. Slabnose had a lot configured, so it was occurring with more frequency.
I've made some changes and while I haven't eliminated it (it can't be eliminated entirely), I have dramatically reduced it. The fix(es) for this will be in version 2.4.