Are you using a 7mm double hex socket? They look identical to the ones I just removed with that. And yes it is the small 5mm hollow Allen key in the centre of the clutch to remove it. It may just need some gentle leverage.
Only the genuine ones have a small enough head to not get hit by the clutch cover. Unless you use button head Allen bolts which always round out.
I got by with a 7mm ring spanner, they are only done up to something small like 6/7nm