I think that LAYA's explanation is not at all clear - hence the question. Do you understand what they are saying?
My best guess of what LAYA is saying is that if the two policies are linked, the excess becomes €250. If this is correct, then why would a couple ever link policies?
I'm insured with VHI so not totally familiar with Laya policies but my understanding is that in general the excess applies to the individual especially where as you say he has a similar policy so you have two separate policies and therefore two separate excesses.
My best guess of what LAYA is saying is that if the two policies are linked, the excess becomes €250. If this is correct, then why would a couple ever link policies?