It can't hurt, but dutasteride is superior to finasteride and they have the same moa, just one is more potent. Adding a little bit of finasteride isn't going to do anything. Now the 15% minoxidil, that could kickstart things on your temples.
I think there are two studies, they may have both just been case studies, looking at finasteride and dutasteride together. None of them compared co-treatement to dutasteride alone. They just add dutasteride on top of finasteride, and find that hair growth improves. Well of course it does, because dutasteride inhibits 90% of DHT whereas finasteride only inhibits 70%. I would bet money that taking both of them together does not reduce DHT by more than dutasteride alone. Adding finasteride to it would be like slightly increasing your dose of dutasteride, there's just no point. .5mg is the top of the dose-response curve.