They've already revoked a number of the Civil War MoHs that were given for mass reenlistments and the like. They revoked 900 in 1916 alone. I don't see anything wrong with recognizing that a mistake had been made, especially when it's the nation's highest award for valor in combat. The citations are very vague (which isn't uncommon for the era), but given what we know about the fight, 20 legitimately earned medals seems unlikely.
For the record, these are the citations:
AUSTIN, WILLIAM G.
Rank and organization: Sergeant, Company E, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: New York, N.Y. Birth: Galveston, Tex. Date of issue: 27 June 1891. Citation: While the Indians were concealed in a ravine, assisted men on the skirmish line, directing their fire, etc., and using every effort to dislodge the enemy.
CLANCY, JOHN E.
Rank and organization: Musician, Company E, 1st U.S. Artillery. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: ------. Birth: New York, N.Y. Date of issue 23 January 1892. Citation: Twice voluntarily rescued wounded comrades under fire of the enemy.
FEASTER, MOSHEIM
Rank and organization: Private, Company E, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: Schellburg, Pa. Birth: Schellburg, Pa. Date of issue: 23 June 1891. Citation: Extraordinary gallantry.
GARLINGTON, ERNEST A.
Rank and organization: First Lieutenant, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: Athens, Ga. Born: 20 February 1853, Newberry, S.C. Date of issue: 26 September 1893. Citation: Distinguished gallantry.
GRESHAM, JOHN C.
Rank and organization: First Lieutenant, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: Lancaster Courthouse, Va. Birth: Virginia. Date of issue: 26 March 1895. Citation: Voluntarily led a party into a ravine to dislodge Sioux Indians concealed therein. He was wounded during this action.
HAMILTON, MATHEW H.
Rank and organization: Private, Company G, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: New York, N.Y. Birth: Australia. Date of issue: 25 May 1891. Citation: Bravery in action.
HARTZOG, JOSHIJA B.
Rank and organization: Private, Company E, 1st U.S. Artillery. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: ------. Birth: Paulding County, Ohio, Date of issue: 24 March 1891. Citation: Went to the rescue of the commanding officer who had fallen severely wounded, picked him up, and carried him out of range of the hostile guns.
HAWTHORNE, HARRY L.
Rank and organization: Second Lieutenant, 2d U S. Artillery. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: Kentucky. Born: 1860, Minnesota. Date of issue: 1 1 October 1892. Citation: Distinguished conduct in battle with hostile Indians .
HILLOCK, MARVIN C.
Rank and organization: Private, Company B, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: Lead City, S. Dak. Birth: Michigan. Date of issue: 16 April 1891. Citation: Distinguished bravery.
HOBDAY, GEORGE
Rank and organization: Private, Company A, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: ------. Birth: Pulaski County, 111. Date of issue: 23 June 1891. Citation: Conspicuous and gallant conduct in battle.
LOYD, GEORGE
Rank and organization: Sergeant, Company I, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: ------. Birth: Ireland. Date of issue: 16 April 1891. Citation: Bravery, especially after having been severely wounded through the lung.
MCMLLLAN, ALBERT W.
Rank and organization: Sergeant, Company E, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: Baltimore, Md. Birth: Baltimore, Md. Date of issue: 23 June 1891. Citation: While engaged with Indians concealed in a ravine, he assisted the men on the skirmish line, directed their fire, encouraged them by example, and used every effort to dislodge the enemy.
SULLIVAN, THOMAS
Rank and organization: Private, Company E, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: Newark, N.J. Birth: Ireland. Date of issue: 17 December 1891. Citation: Conspicuous bravery in action against Indians concealed in a ravine.
TOY, FREDERICK E.
Rank and organization: First Sergeant, Company C, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at:------. Birth: Buffalo, N.Y. Date of issue: 26 May 1891. Citation: Bravery.
TRAUTMAN, JACOB
Rank and organization: First Sergeant, Company I, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: ------. Birth: Germany. Date of issue: 27 March 1891. Citation: Killed a hostile Indian at close quarters, and, although entitled to retirement from service, remained to the close of the campaign.
WARD, JAMES
Rank and organization: Sergeant, Company B, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: Boston, Mass. Birth: Quincy, Mass. Date of issue: 16 April 1891. Citation: Continued to flght after being severely wounded.
WELNERT, PAUL H.
Rank and organization: Corporal, Company E, 1st U.S. Artillery. Place and date: At Wounded Knee Creek, S. Dak., 29 December 1890. Entered service at: Baltimore, Md. Birth: Germany. Date of issue: 24 March 1891. Citation: Taking the place of his commanding of ficer who had fallen severely wounded, he gallantly served his piece, after each flre advancing it to a better position.
ZIEGNER, HERMANN
Rank and organization: Private, Company E, 7th U.S. Cavalry. Place and date: At Wounded Knee Creek, and White Clay Creek, S. Dak 29-30 December 1890. Entered service at: ------. Birth: Germany Date of issue: 23 June 1891. Citation: Conspicuous bravery