Breen (1989) listed two "for sure" Proof 1824/2 Dimes and one questionable example that may have been cleaned to appear as a Proof.
Davis et al (1984) wrote "Three proofs reported. Finest seen is Proof-67 (Lot 166, Stack's Bareford Sale, Oct. 22, 1981; ex. Lot 174 Numismatic Gallery's Menjou Sale, June 15, 1950)."
In 2002, PCGS certified a Proof-65 1824/2 Dime. In 2006, PCGS certified a Proof-66. Both coins were cracked out subsequently and the latter coin was graded PR67 by a competing grading service.
Sources and/or recommended reading:
"Walter Breen's Encyclopedia of United States and Colonial Proof Coins 1722-1989, New Revised and Corrected Edition" by Walter Breen (1989).
"Early United States Dimes 1796-1837" by David Davis, Russell J. Logan, Allen F. Lovejoy, John W. McCloskey and William L. Subjack (1984)