It all looks a bit odd to me too.This chap is a Colour Sgt. or WO2 so not someone who's only been in for 4 days.He appears to have been discharged because he had no teeth whereas this chap looks like he has a full set.If he re-joined why isn't there a medal card for him ?Also I find it hard to believe this is a 1918 photo. You don't even see older women dressed like this that late.