Geobase also shows the name changing here - to be precise, at southernmost merge/split points of 401 ramps here, so that if you're going northbound to 401 you are on DVP, going eastbound to southbound you go from 401 to DVP, going westbound to southbound you go from 401 to 404 to DVP.

We could probably check City of Toronto's GIS to see what they say too.