Thanks to the Home Computer Club for sending me the editor's choice I've been able to recover the tapes - at the time I didn't even have a 128K machine, so I don't remember why I kept them
Good news - apart from block timings there's nothing different between the Rod-Land compilation and the standalone release
Bad news - the Double Dragon tape is missing the last 3 sets of level data - the tape is about 5 minutes too short!
Anyway, a bundle of TZXs are here and the WAVs here
Cheeky poke for Double Dragon III
Spoiler
You can enable "invisible" mode by poking 35371 with 13