Nope, not Duncan. I've checked quite a few of the likely suspects, and the tops I can find is Ben Ogilvie with 8. There are a couple where retro sheet doesn't have the daily player info, so it would take a while to search day by day. Charlie Jamieson from 1928-1929 had 5 SBs and 25 caught stealing. That's a possibility.
Found one better. Pete Runnels for the Washington started his career with a string of 13 consecutive caught stealing (0-3 in 1951 and 0-10 in 1952). He was 3-7 in 1953, but I don't know the order because retrosheet does not have the dailies. So, Rivera is at least one from the record.
Another...Eddie Yost for the 1957-58 Washington Senators (Hmm, I'm sensing a theme) was caught 13 straight times. I know that one's no longer than that, because retro sheet has the daily. He stole a base April 30th, 1957, then was caught 11 consecutive times in 1957. He was caught twice more before stealing one on July 23, 1958
Here's a list as complete as I can make since 1920:
Chris Cannizzaro 14, 1964-1970
Pete Runnels 13 (could be longer), 1951-52
Eddie Yost 13, 1957-58
Zeb Terry 12 (could be longer), 1920-21
Jay Buhner 12 1990-93
Some other possibilities:
Charlie Jamieson, 5 SB in 30 attempts from 1928-29
Joe Sewell, 3 SB in 19 attempts in 1927
Red Kress, 6 SB in 28 attempts in 1930-31
Bill Knickerbocker, 7 SB in 33 attempts in 1935-36
Eddie Mayo 4 SB in 20 attempts in 1947-48.
Larry Gardner 3 SB in 23 attempts in 1920
Hod Ford 1 SB in 13 attempts in 1924-25
Bobby Doerr 6 SB in 26 attempts in 1938-39
So, Juan could very well be 3 away from breaking the record.