As @jammco mentioned, it works that way. As a software developer, I can see a pattern with how the scent capsules work. Here is my analysis:
There is a time-frame for each dinosaur to appear. After activating, we see a dino immediately(within first five seconds). No matter what. The next ones would appear exactly after the two minute interval.
So for the Normal capsule, we get a total of 3 dinos. For rare/epic scent, we get 10 dinos. And these dinos are basically depends on the time of the day you are activating the capsule. For example, if you activate it in the day time, you can expect Apatosaurus/Stegosaurs and if you did it in the night, we might see a Velociraptor/Kaprosuchus(which only spawns at night). Hope this is useful.