is there a better way than “replace” behavior during the import, to avoid duplicated images

Question

We import products using CSV files via the backend. FireGento_ExtendedImport2 is installed as well.

Now we saw that images are added again and again to a product's image gallery on each import.

We tried using the replace behavior which seems solves this at first glance --- but I feel it is ineffective to re-create thousands of products again and again.

Is there another way to avoid duplication of images during repeated imports?