Custom model- add documents

Question

So I am creating a Custom model for a document, as per requirement I need to add 5 minimum document of that kind label them and then Train. My question if I again want to train a model in the same project would I be required to delete the previous labelled documents or I can add 5 more new document type and train, my concern is it will again train 10 documents with 2 different types of document which can give conflicting results. Thoughts?