Oh, no - it only gave me one alternative (which I tried to select and it ignored me).
I'm not sure how much people care, but for the sake of clarity in case anyone does...
Google Maps gives me three out of four possible routes - with the choice of which ones changing for no obvious reasons (if I move the start position just a few feet, it may or not switch between SW and W options)
Google Navigation gave me S and SE initially, then I got in the car and it gave me S and SW, but when trying to select SW it still made me go S.
On the way back, it gave me choice of reversed equivalents of W or S routes, claiming they were both about the same time.
In both directions, the W route is horrible, since it involves lots of traffic lights and relatively narrow high street roads through Sutton/Carshalton/Waddon, so no idea why it's shown as an option (it doesn't involve motorways, but I haven't ticked the "avoid highways" option, and even if I do I get given three entirely different routes - I guess A3 is considered a highway (is a three-lane dual-carriageway with national speedlimit).
I'm not really sure what mistake I'd report? That Maps / Navigation give conflicting primary routes?
But that's less a mistake and more that they haven't bothered to implement traffic awareness into the Maps route selection thing, so would be a feature request (as would the advanced traffic awareness thing).
They oddly updating streetview right outside my house recently. A few images down the road and it's 2009 and up the other end it's 2011. No idea why they didn't do the whole road, the old photos are pretty dark and grim, which to be honest is more representative of the weather round here!