you should post it as an attachment. but, ur problem is fortunately a common problem.
what is happening is that the trigger is being run for more than 1 player. for example, if u selected players 1, 2, and 3 for "players" (before conditions and actions,) and all 3 players were in the game or computers, if the conditions were met for each player it would be run for each player. for example with this:
players: 1, 2, 3
conditions: always
actions: create 1 marine at location 0 for whoever
it would make 3 marines. to fix this you would just select 1 player instead of 3, or select the force, etc... play around with it to get what you want!
