Remeber that "coming in contact with food " is not always as direct as it sounds. You may not be cutting an orange to eat it in the next second, you may be using the knife to prepare a rabbit or fish in the cooking pot.

Also, coming in contact with bad stuff is not only when you use it to open a container of rat poison. Even when you use it to cut a small branch and the plant happens to be poisionous, some of its juices may be sticking to the blade when you touch food with it.

Haviung two blades is good but I wonder how practical it can be. Alright we all have many blades around us, but how can you stick all the time to the "food knife" and "dirty knife" classification all the time ?