Title format

[L.]

I was directed to this group after posting to GR Help, hope I'm now in the right place.
I have added my author page book title as per instructions (with a colon separating the main from the sub). However, on the 'actual' book's cover, the subtitle is differentiated from the main title through size and italics, rather than a colon. I already have a colon 'within' the subtitle. Is it acceptable to have two in the overall title? Or should I set it up another way?

[Emily]

I think it looks fine the way you have it.

[L.]

Thanks, Emily, I'll leave it with the two colons then.