Good find, I could not locate the two in the Federal census.

I do not know where you found Sr. & Jr. enlisting the same day, However, this is a rather interesting find. Both on sick furlough together?

John Black, Private, Company H, 17th Regiment Alabama Infantry, recorded on the January 1862 Regimental Return as absent, On sick furlough from Jany 20, 1862 for 20* Clauseville, Ala. [John Black record, card #2]

* Note, the word “days” as found on J. W.’s record is missing

……

J. W. Black, Corporal, Company H, 17th Regiment Alabama Infantry, recorded on the January 1862 Regimental Return as absent, On sick furlough from Jany 20, 1862 for 20 days Clauseville, Ala. [John W. Black record, card #5]

M311: Compiled Service Records of Confederate Soldiers Who Served in Organizations from the State of Alabama