Several folks (including Daniel Frank and Vince Waldron) point out that the final episode filmed for the second season ("All About Eavesdropping") wasn't aired until the following year. So that may go half the distance to explaining why the DVD release of Year Two of The Dick Van Dyke Show promises 31 episodes when there were actually 33.
Vince is doing some digging to find out what's up with this, so we may have an answer here before long. But he tells me that from everything he's heard, these DVD releases are first-rate productions both in terms of video quality (and completeness) and in unearthing some amazing extras. I'm so grateful to him for this info that I'll remind you that he authored The Official Dick Van Dyke Show Book, which is rightly subtitled, "The Definitive History and Ultimate Viewer's Guide to Television's Most Enduring Comedy." You can order a copy of the new, revised and expanded edition from Amazon by clicking here. If Vince hadn't written this book, I would have, except that I wouldn't have done half as good a job as he did.
With one exception. Vince inexplicably forgets to mention the Gold Key comic book version. I'm sure he'll correct this in an upcoming edition but other than that, it's everything the subtitle claims. Plus, it's Fair and Balanced.