Hi,
You can solve this by closing the active model. Therefore it would not be in the list of the opened/loaded models:
1CC "Modeling" GET_ACT_MODEL
2SET nActiveModel: (modelid)
3CC "Modeling" CLOSE modelid: (nActiveModel)
If you need the model after the export again opened than open the model as follows:
1CC "Modeling" OPEN modelids: (STR nActiveModel)