I was wondering why so few posters were chiming in on the Favour Etiquette thread. Now, I see that y'all came over here!
I don't think it's rude to give people the same gift, and I think it's presumptuous to believe that no thought went into the gift-giving because they are identical (now, what the identical gifts actually ARE is a different story, as one PP said something about brightly-colored discount hoodies). I prefer not to give people the same gift (because then the gift will often have no meaning for me). However, last year DF and I gave the same gift to his cousin and her family and my sister's kids. We bought reusable popcorn containers, Netflix gift certificates, microwave popcorn and various theatre-size boxes of candy, and I made movie gift baskets for everyone (one big one for his cousin's family and two little ones for my niece and nephew). While they weren't as personal as the gift baskets we made for his other two cousins, a lot of thought still went into them (one cousin and his wife got a pet stuff gift basket -- Litter box "basket," big cat toy and big dog toy since they're so into their pets and the other cousin is a vegan so his gift basket was a serving tray with several bags of different dried fruits and nuts).