Make sure you include the not isRound part of the conditions for your breaks, and isRound for your rounds. If, for a round, you just use roundNum = 2, it can fire for breaks because the roundNum variable is still valid during breaks. For example, if your first break is directly after round 2, then during that break the round number is still 2 since the tournament has not yet advanced to round 3. Using isRound for your round events will prevent the round events from firing during breaks.
isRound and roundNum = 2
The state = 2 part that Stuart mentioned makes sure the tournament is running, and not in a countdown. That would prevent your blinds announcement at the beginning of round 1 from firing when the countdown starts (if you use a countdown).
isRound and (roundNum = 2) and (state = 2)
FYI, I added isBreak in version 3.2. Logically it's the same as not isRound, it's just more intuitive.