Since the only muster roll he's on is the roll transferring men from the 155th PA back to the 91st, it seems likely his name is a misreading of someone else's.
As far as I can tell, no Charles from company E was transferred to the 155th; the closest match I have found is Francis Harrigan--but his compiled service record includes a card that appears to be from the same muster roll, which makes it very unlikely that this card could actually be Harrigan's.
(See letter, Joseph H Sinex to Captain A S Marvin Jr, 30 December 1863.)
During the war
He was a private, in company E.
[sources: 1, 2]
He was listed as present on the Detachment muster roll of the 91st regiment Pennsylvania infantry, January-February 1864, Warrenton Junction.
(This was the detachment transferred to the 155th Pennsylvania while the veterans were on leave.)
On 25 February 1864, he was transferred--presumably back to the 91st from the 155th.
1index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania
[compiled service record, 91st Pennsylvania, Charles Harrigan]
[transcribed 12 April 2015, from two images, obtained from the National Archives and Records Administration]
Co. E, 91 Pennsylvania Inf.
Private | Private
[the rest of the card numbers are blank]
Number of personal papers herein [blank]
Book Mark: [blank]
See also [blank]
H | 91 | Pa.
Pvt, Co. E, 91 Reg't Pennsylvania Inf.
Appears on a
Detachment Muster Roll
of the organization named above,
for Jan. + Feb., 1864
Station Camp at Warrenton Junction
Due Gov't, [blank]
Remarks: Transferred Feb. 25 /64.
Has no descriptive list.
Only roll on which borne
This detachment was temporarily transferred to and mustered with the 155 Reg't Pa. Inf. per S.O. No. 177, Jan. 1, 1864, and S.O. No. 30, Feb. 25, 1864, Hd. Qrs. 2d Div., 5 A.C., the 91 Reg't Pa. Inf. having re-enlisted for three years.