Monte Carlo simulation explain like the I’m 5

I’m new to the Monte Carlo simulation and I’m trying to do project risk analysis. People have told me that if I apply multiple activities to one risk in the simulation I’m double dipping (the simulation will compound the risk and increase it’s cost by double). I’ve no evidence to support this theory. I believe all activities to the risk should be included regardless to get a better analysis. Am I wrong? Please help me understand this.

analysis apply cost datascience evidence multiple people project risk risk analysis simulation support the simulation