[DiapDealer]

It's a meta tag; they're supposed to be superfluous. But they often provide a historical trail of where a file has been, and/or what's been done to it. Delete them or don't. There's only a handful that might be relevant where making Kindlebooks is concerned (and of course the calibre ones that some devices/apps have adopted for library management ... but end users will just have calibre add those regardless).

My advice??? Don't stress over them one way or another.