Right? I would be pretty mad at whoever sold these frogs as African Bullfrogs.
Also, I looked up the Tarahumara frog. In Arizona it is protected, and some resources say it has been extirpated from the US. Between the rarity and protected status of the frog and the tadpoles looking slightly different(more tail coloration/iridescence on Tarahumara Frogs)
I think these may simply be the ever-common American Bullfrog. Below is a link to a picture I found on google images( I do not own it etc) of a American Bullfrog Tadpole. I think the spots match pretty well, as well as the drab coloration. American Bullfrogs are very common, as tadpoles are often sold at pond supply stores to help keep ponds clean, as well as at some pet stores, aquariums etc.
https://i.pinimg.com/originals/8e/db...1058b4eac2.jpg
Also, a link to the original thread so Herpin Man can see the tadpoles:
http://www.frogforum.net/showthread....rican-Bullfrog
All that being said, If they are Tarahumaras that'd be really weird and very interesting.