The statue in Boston is a copy of the Emancipation Memorial in Washington DC. The latter is the one that the freedmen actually paid for. The Boston statue was a gift of a civic minded benefactor, who thought that emancipation, freedmen, and the martyred Great Emancipator were worthy of commemoration and remembrance. Clearly he was not progressive enough for Boston today.
I do not know if the Boston copy was made from the original mould by the original artist.