It took me some hunting to find this on Footnote.com. Is the receipt you refer to misfiled with a different Allen?

J.M Allen
Private
Co. D
Deneale's Battalion (later Deneale's Regt Choctaw Warriors)
enrolled Lukfahtah, March 14, 1862

Lukfahtah (or Lukfatah or Lukfata or Lokfata) is on the west side of Broken Bow, McCurtain County, OK. There was a mission school there as early as 1841.

Leaving Broken Bow going west a mile we come to Yazoo River, which is the boundary line between Eagle and Boktuklo counties and which was named for the Yazoo River in Mississippi...

Leaving Yazoo River going West one mile you come to Lukfatah, a settlement and postoffice. Rev. Loring S. Williams, who started Beth-a-Bara School, also started a school there and called it "White Clay." The word "Lukfatah" is a translation of "White Clay." Lukfi means "dirt" or "clay" and Hatah means "white," "white clay."

Previous to 1855 there was a white man by name of Skelton who kept a store at this place, and his store became headquarters for any payments made to the Choctaws in that part of the country. It is said that during the payment of 1855 he paid out in gold all the money that was paid to Choctaws in that part of the country. The place became known as Skelton Depot. Skelton Depot, White Clay and Lukfatah are all one and the same place. [Chronicles of Oklahoma; Volume 10, No. 4; December, 1932; RECOLLECTIONS OF PETER HUDSON]

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5. Bok Tuklo Kaunti—(No English name). The Choctaw name means "Two Creeks," from bok the word for "creek," and tuklo meaning "two." The fact that the two creeks Lukfata Creek and Yasho Bok, ran parallel to one another from north to south, clear across the county may have had some significance in naming the county "Bok Tuklo." There had been a village of Choctaws, with the same name, early in the 18th century. [Chronicles of Oklahoma; Volume 8, No. 3; September, 1930; ORGANIZATION OF COUNTIES IN THE CHOCTAW AND CHICKASAW NATIONS; Muriel H. Wright]