If there's only one person using the app they'll see that same entry 100 times.A common design for something like this is a junction table that allows clients to see all the resources, but when the client has already voted, the entry is marked as "read" or similar. Most email uses this sort of design. This allows the client to ask, "What's new?" and get a good answer without having to look at the same entry many times.
Let me put together a little script to show some ways of thinking about randomization. If you're getting too much predictability from the PHP rand() and mt_rand() functions you may want to consider using shuffle() instead.