Not really. I had to explain it to them (CGU)a couple of times and get a new schedule sent out, but they got it right in the end. I got them to actually state on the policy that the property consisted of a house and rear bungalow, but my understanding is that regular building insurance covers all dwellings on a single title anyway. I had to stress that it was a single title a number of times.
My insurance broker (with a CGU policy) made it easy for us to insure a multiple dwelling property.
There is a single cover for the building(s) - in our case a townhouse converted into 2 flats - which insures everything on the title (both dwellings).
Then for landlords insurance we took out a separate policy on each of the dwellings, as they are separate tenancies.
Note that we had to explain carefully to our broker what the property was - and it made it more confusing that there were two of these properties on separate but adjoining titles, for a total of 4 tenancies... but they got it and worked it out for us.
The moral of the story ? Get yourself a good insurance broker - they'll sort it out for you !