No - the point is to quickly detect random websites that simply duplicate known favicons! Matching hashes can only occur in these cases:
- the site is a careless impostor
- the site is the real deal
- a hash collision
- the site is a careless impostor
- the site is the real deal
- a hash collision
Case 3 must exist by the pigeonhole principle given that the hashes are smaller than most favicons. Otoh, if it does show up, you can exclude it by doing a full comparison.