I was thinking this was a Blood-Leaved Peach, which has a pretty cool story behind it... but the Blood-Leaved Peach is clingstone (what you describe above sounds more like a freestone), and the historical description of Blood-Leaved Peach would have the leaves turning a dull green later in the year.
Anyway, here is the story behind Blood-Leaved Peach:
Quote:
An account is given of its origin worthy of the days of Mythology. " The variety was found on the battle field of Fort Donelson, in Kentucky, and the Southern papers tell that a Southern general, wounded to death, sucked the juice of a peach, and threw the stone into the little pool of his blood by the side of him, from which sprang this tree with blood-like leaves." Mr. Berckinans, in the Rural Carolinian thus describes it. "In the early portion of the year, its foliage is of a deep blood-red color, but gradually fades as the weather becomes warmer, when it assumes a dull green appearance. Fruit 'medium, slightly oblong, somewhat flattened; skin white, with a pale red wart, and a few pale red spots or stripes; flesh white, juicy, well-flavored; clingstone; ripens beginning to middle of August. We would class it as very good in flavor, but deficient in size." The Gardener's Monthly says it ripens in Philadelphia the last of September, and that when making second growth in August, the leaves are nearly as brilliant as in spring.
Here is another decription of Blood Leaf Peach from the Cyclopedia of Hardy Fruits, but again, this is described as "unproductive", which doesn't sound like what you're describing:
http://goo.gl/auQqL
I am flipping through the Cyclopedia to find other possibilities. Some I noticed off the bat are Carman, Chinese Free (seedling of Chinese Cling), and Belle to name a couple.