[doubleplus]

I just like books with post-colonic explanatory subtitles, but it looks like I'll be taken care of as well.

Yes, I made that word up.

[pg]

You could call them prolapsed titles.

[MaysonL]

Interestingly enough, W.P. Montague's book The Way of Knowing, had a post-sesquicolonic explanatory subtitle:

The way of knowing;: Or, the methods of philosophy

at least in early editions, the sesquicolon seems to have been replaced by a mere comma in the latest reprintings.

[jauco]

"colons: why bother to come up with clear title when you can explain yourself"

From the same author as "How to become extremely successful at writing self-help books"