Actually, this may be a good sign, assuming the comment on your following ability was genuine and not purely motivated by a desire to sell you lessons. (Remember dance instructors have to eat too.) While some professionals do 9 or 10-dance competitively, most specialize in either Standard (Smooth) or Latin (Rhythm). And pros take lessons from whoever does a particular style....or technique....or choreography....best.
So if an instructor suggests taking one style from him and another from a different instructor, he may be trying to steer you toward the best instruction there. Certainly he isn't trying to get all your lessons for himself, which I'd think would be the case if all he was interested in was $$!
If you're getting the impression this is being done on the sly, maybe it is. But that doesn't necessarily mean bad things for you. Perhaps the second instructor will get a slightly higher percentage of the money you already paid for lessons and the owner will get a little less. Perhaps the other instructor just had a time slot open up, and if word gets out before he fills it, a couple he DOESN'T want to teach will be assigned to him. Could be some other reason too.
In any case, from the people I've danced with, I'm convinced having more than one instructor simultaneously makes for a more flexible, well rounded partner. Especially at the start. Just adapting their frame and lead to 2 different teachers makes men much more pleasant to dance with. They learn to automatically tune in to their partner instead of dancing by rule and mechanics. I've had as many as 3 instructors at once, and it's helped my following skills enormously. Plus while one is concentrating on some minute detail of Cuban motion week after week, another will be working on musicality in waltz or expression in tango. Less boredom, less chance of burnout.
As for the ages of the instructors, well, dance is a very physical activity, rough on the body, and pays poorly except for top coaches. By definition, there can't be very many top coaches. Then there's the hours; working nights and weekends is OK for college students, but imagine trying to sustain that lifestyle while schlepping kids to soccer practice or finding time for meals with a spouse. That's probably the reason why dance instructors are often young singles or married to each other.
