Unfit for further military service?

[Greenvale]

I have a relative who appears to have enlisted twice and was killed in France during this second enlistment.
Arthur Edward Cunningham bn. 1890 in Birmingham. He enlisted in the Royal Warwickshire Regiment 8th Battalion on 17th July 1913. His Regimental number was 1986.
He was discharge as medically unfit due to Epilepsy on 9th November 1915.
He is then listed as killed in action whilst serving with 6th Battalion Royal Warwickshire Regiment at the battle of the Somme on 17th August 1916 and is buried at Poziers British Cemetery, Olliviers La Boisselle. Regimental number 5312.
I cannot find any service records for him under this number (presumably destroyed in the blitz). The question I am asking is would he have been recalled for service or did he re-enlist on his own accord?
If he was recalled wouldn't he have retained his original regimental number

[josey]

Is it PLUS something else as well as Variocele?

[jim1]

He would have re-enlisted. It's wasn't that unusual.
The 1/8th. was a TF outfit so he would have been embodied after the outbreak of war but didn't go overseas with them (March 1915).
His only overseas Batt. was the 1/6th. this was also a TF Batt. & part of the same Brigade as the 1/8th.
It may be a case of him being re-assessed after conscription was introduced.
or
He may have joined under the Derby scheme late 1915 which would have given him some say in which Regiment he went in.

[jim1]

As an aside the diary states they were in trenches around Authuille Wood when the Germans launched a counter-attack. He was one of three men who died as a result.
Square X1 on this map:
https://maps.nls.uk/view/101464804

[Greenvale]

Jim, thank you so much for your very informative replies.