skrapers can't know if a certain artwork is updated or not unless they keep metadata and the build in skraper does not do that. However certain skrapers always overwrite files but i'm not sure if the build in skraper does this. If it does not i know of a way to easily identify these files and erase those screenshots so they get redownloaded if you scrape afterwards.
Most of the times (depending on where your scraper got the data) the same screenshot is used to show "not working" screenshot or something so you need a tool that can search for such identical pictures by CRC and lets you delete them. one such tool is
dupterminator it finds duplicate files by comparing md5 hash.
You let the tool search the files and you find one screenshot (show large files in the dir view in explorer.Exe) and locate it in the search results by sorting on the checksum column first and then all other files wich use the same screenshot should be in the same group. Highlight the files and press del button and they are erased. After doing that rescrape your files and it will download new screenshots for the files you had erased.
