Just my opinion: One Bond. Within the movies, he's had many faces, only due to personnel changes. All the same character, the same man. The prologue to OHMSS is simply a throw away sequence to introduce the audience. Non-canon, just like the original Casino Royale.

Where you stand on Never Say Never Again is personal choice, but I always considered it an enjoyable oddity that fits nicely when not concerned about continuity, just entertainment. I think that's a good idea for modern serial fiction: disregard a continuity and enjoy the storytelling.

Again, just my view. Your mileage may vary.

Will