Please show a screenshot of the advanced action. My suspicion is that you are using the same name for an action and another object or variable. Captivate requires that each name is unique. Your explanation points in that direction. If you want to use a similar action for multiple events, in some cases it may be better to use a shared action instead of duplicate advanced actions.
Please check the names of the buttons, variables, objects. Do NOT use the same name for an advanced or shared action.
When a copy is generated a number is added, which is NOT random but follows a logic. That is to prevent using same name multiple times.
See also http://blog.lilybiri.com/tip-1-labeling-advanced-slash-shared-actions