One of my girls has dealt with this problem as well. To try to cut down on the frequency I feed her Iams Adult indoor cat and hairball control food. (it works out well for me that she's an indoor cat who has hairball trouble...and that they make the food with both things in it.) Last year I got remarried and my new hubby came with another cat, who eats a different kind of food. Since we didn't have a good way to separate who eats what my girl started eating her new sister's food. I noticed this and started mixing their food together, so my girl would still get the nutrition, etc. from the food she'd always eaten. Sadly, we've had an increase in hairballs. (the other food isn't hairball control.) I'd love to be able to go back to feeding her just the Iams but I don't think my husband will go in for eliminating the other food.
Something else I've noticed lately is that one of them is coughing up not-chewed pieces of kibble. I'm not sure exactly what that's about but I suspect someone's trying to eat without crunching the pieces up properly first!
