Riverlynn wrote under chapter 26 that "it's been confirmed recently by the publisher (on twitter) that it was an error in Galbraith's part."

(There are many similar mistakes throughout the book, I never had any doubt whether this was a mistake or intentional.)

Yes. I noticed this too and thought it out of character as Cormoran is known for his great memory and attention to detail.

Grey said
I just noticed in the audiobook version the narrator says “Ciara Parker” instead of Ciara Porter when Strike is mentally going through his list of liaisons. 

Yes, I noticed that as well in the ebook-version. It's a bit annoying, I feel that someone should have noticed the mistake in the editing process. (But besides that small distraction I'm loving the book so far).