Moved to ClientSide Technologies forum.
jamjam wrote:Is it possible to specify 2 locations for an image in html?
Using strictly HTML only? No, it's not possible.
You could use some Javascript that loads the image and attaches a function to the image object's onerror handler that would then load the backup image, but unless you're familiar with Javascript that might be a little tricky to do.
Here is a page that talks about using Javascript to check if an image loaded without errors.