Hi
Unfortunately, by default, when Campaign uploads the image it generates an unique image name and there is no option as in CampaigN Classic to conserve the name. What you might have to do is to contact Customer Care to see if the image could be renamed on the server, I've never made such request so I can't say if it will be accepted, worth a try. and If an option exists in the back-end to conserve the original fie name, having a Support ticket might help to set it. Again I don't know if such option exists either...
Thanks
Denis