sentry/analyse_hash_collision: Type contents + add a diff entry

This allows to more clearly see the difference and distinguish betwee real
collisions from "falsy" ones:

• real: in "difference" entry, there are at least 2 algo in collisions (most

likely 3 out of 4)

• "falsy": in the "difference" entry, only 1 algo in collision. And the diff is

an extra "25" which inserts itself somewhere in the hash