You might have seen an author at a book fair or event autographing copies for fans by crossing out their printed name on the title page of the book and then signing their name in ink instead.
What ARE they doing?
Authors love their fans and the relationship between writer and reader is an important one. It's not something to be glossed over or denied.
Many extremely important people often have representatives or secretaries sign items that need to be sent out just because the schedule will not allow them to personally sign everything.
Advanced letter etiquette indicates that the formal proper name should always be typed, but then struck out and hand written to express less formality, and thus, a closer relationship with the person you are addressing. As in the way of letters, the same is indicated when an author strikes out their own name and handwrites it to you instead.
Of course, you'll have been there when it happens, so you know that it was the author who personally signed your book for you. But the strike out is to say, in proper etiquette, that they themselves, feeling closer to you than a total stranger, as a sign of appreciation for that reader/writer relationship, has personalized it just for you.
Have you done this for books you're signing for fans? Have you received a signed copy that was done in this way? As Paul Harvey would say, now you know...the rest of the story!