I see that it is a single post that you are referring to so if there are more images other than a single image in a single post then I think the plugin is configured to repeat the title tag. However, I do not see any harm seo-wise due to all images being in a single post. However, In the SFI settings, try inserting different inputs in the “Title attribute box” eg. %name %category, %tag %name, etc. and see if it works.
If you are using repeating same image titles for different posts then probably you can worry about seo.