Well, after poring over the nearly 160,000 Retrosheet gamelogs of NL/AL games through 2012, it appears that there have been approximately 130 instances of one player’s last name being the same as the first name in the next batter in the lineup.
The first occurrence came on September 13, 1916 in the second game of a doubleheader between the Cardinals and Phillies. The Cardinals third hitter, SS Dot Miller, was immediately followed in the batting order by 2B Miller Huggins. The most recent occasion (prior to 2013) was April 12, 2011 when the Mariners SS Brendan Ryan was followed by CF Ryan Langerhans in their game against the Blue Jays. There has never been a “trio” in a single lineup, though on May 30, 1958 the Dodgers had C Sammy Taylor, 2B Tony Taylor and P Taylor Phillips as the bottom third of the order.
The most frequent “name duo” in history is Casey Blake and Blake DeWitt, who were in the same lineup in the same order 41 times for the Dodgers between 2008 and 2010. Here is the list of lineup pairings for all 130 occurrences through 2012:
And here is the list of each occurrence by date: