In his bookshelf, Khan has two copies of John Milton's Paradise Lost. One of them looks newer and thinner, and it also contains Paradise Regained.
Is there a significance in the fact he has two copies? Or is it just a mistake by the prop department? Have the filmmakers discussed this?
Note, I'm not asking why someone like you or me may have two copies of a book. I'm asking if there are canonical in-universe or out-of-universe reasons for Khan to have those two copies of Paradise Lost (e.g. he loves it more than, say, Moby Dick; the producers wanted to stress he's more Satan than Ahab; the Regained copy belonged to his wife and when she died he lost the possibility of redemption; two people from the prop department brought their own copy of the book and they decided to use both; the font of the main book title looked not enough visible and the prop department had to add a second copy so the viewers don't miss it; etc).
If no canonical reason exist, the best speculation "within the spirit of canon" will be awarded the green mark.