Pretty pathetic on the part of the US band. If anything, they will benefit from a far more successful band sharing the same name - at least some people looking for the UK band will find the US one and eventually buy their music.
Three times their profits and damages of £600,000 is totally out of proportion.
If the project name I'm working under currently was used by another band who became as famous as the UK One Direction then I wouldn't be pissed off and sue anyone. As it stands someone else is using the same name already. And seeing as it's the name of a couple of hills in shropshire/herefordshire I reckon nobody would really care anyway.