I don't usually collect photos, but along with the Matty horizontal, the Cobb leaning on bat is my favorite E / D card pose. I am not aware of another example of this photo. (If anyone is, please let me know!)
The letter of provenance is pretty neat -- it comes from a direct relative of
Dr. Stewart D. Brown Sr. and Jr. -- and says that Cobb gifted the photo to Dr. Brown Jr.