It is far more important to make sure you do not structure your hashtables so collisions can occur. Eg avoid strings and handles being in the same field for the same table as if done improperly I believe you could end up with a chance of 2 of them having the same index (although very small).
EG for object types you should use your own hashtable and the same for handles and strings. Although like I said the chances for collisions are near none but I do think a string and a handle and an object type can shair the same value yet represent different things (do not shair the same index system.
However I am yet to encounter a collision in such a way so I can not confirm its existance but I do believe they can occur.