- create two new pastes (for example, ID 9 & 10)
- remove the pastes ID 9 & 10
- create new paste quickly (before anybody other have chance to create one concurrently)
- compare old address with the new paste. The new paste will have ID equal 9. Subsequent one will have ID equal 10, and so on.
If you remove one or more last pastes, the new paste to be created will re-use IDs of former pastes. This will lead to people finding completly unrelated pastes under same ID, if the previous one has been deleted and was the highest numbered one.
I'm not entirely sure whether it's abut the most recent paste in sense of time, or the highest numbered one. I guess it's the later.
The problem is probably caused by default SQLite semantics.