My Signal Orange UK 70S had two sister cars, same colour, seemingly all registered by Porsche UK. Demonstrators or Press cars perhaps. They were early in the production run. 
I was contacted by the owner of one of the other two orange S-es - he had recently finished the resto. It was a pleasure to be invited to see that car last weekend - thanks! - and to check out the fine details. It's been beautifully done. Something to aspire to.