Almost always, where the opposite of one thing is, the opposite of that thing is also found. Dumbledore was "darker" in his younger years. Of that we have evidence, yet in his older days he seemed to be more light. My theory goes back to the origional brothers of the perveral story..... What if "death was a very abnormally powerful wizard who was originally light but then became dark in his older years. He then gave the objects he made to the brothers and eventually they came to Dumbledore.
In the Order of the Phoenix, I believe it was mentioned by an elderly wizard that Dumbledore was capable of doing things with a wand that he had never seen. What if we were mis-Interpreting this as after he had dueled Grindewald. What if the elderly wizard ment before such a time.
My theory is that Dumbledore is the "reincarnation" or the lighter version of "Death" and instead because of his better nature this time; he turned the objects away for the better. That is to say, that Dumbledore is not "Death" per say. Rather that he was the better image of death.