Did you buy The Walking Dead Vol 17 in trade paperback this week? You might want to check you got all you were expecting.
There are a number of reports of misprinted volumes with the last chapter, 102, replaced with a repeat of chapter 101.
Now, 101 is a very good issue of the comic. But there's no need to read it twice in a row. And miss out the subsequent comic.
It is expected that Image Comics will send out a recall notice to affected stores, so you might want to get in touch with your local comic shop and either get a replacement from their unaffected stock, or arrange a replacement for a later date. Online services such as Amazon are usually responsive to this kind of thing too.