The following tintype photos have been collected from various members of the Dickinson family. Collectively they appear to be from the same time period.
We know Harry had a brother named William Henry Dickinson, who appears to have been named after their father, William Dickinson of Sheffield. (Harry subsequently named his eldest son William Henry Dickinson as well). In the first photo, shown below, Harry is sitting with his brother, William. In the second photo, Harry is standing with another gentleman and the writing appears to say "Pa & Ben Allinton" at top. If anyone has information, please comment below. Harry is shown alone in the last two.
See the Dickinson page for more about this family.