I just got a lot of different chocolate flavors from FW and when prepping each I noticed they all smell the same, with exception to the chocolate mint. Is this normal? Does the unique flavor come out after it steeps for awhile?
Synthetic flavor concentrates are created by combining various compounds, at various percentages, to achieve a desired result. These compounds may, or may not have an identifiable odor. It stands to reason that similar flavor profile, like "chocolates," would share same/similar compounds... so the aromas could often be similar too.
The compounds that differentiate the different chocolate-based profiles, may or may not, have dominant enough aroma to compete with the primary "chocolate" smell you are detecting.
This is before we even factor in our own personal sensitivity to different scents. It is no uncommon for individuals to be "blind" to different smells.
Also remember; though taste and aroma are often related, it is no guarantee. Durian fruit smells like a cross between fetid garbage, and an adolescent's sweaty gym socks; yet tastes like a sweet complex custard. Limburger cheese smells like a dog-with-intestinal-distress' flatulence; yet tastes mild and buttery.
Taste can be enhanced by aroma and vise-versa. I would suggest tasting each concentrate, as a stand-alone mix, to see what your own perceptions pick up.