Percival Bland's Proxy and The Missing Mortgagee

These are two short stories from the collection THE GREAT PORTRAIT MYSTERY: ""PERCIVAL BLAND'S PROXY"" and ""THE MISSING MORTGAGEE"", wherein the brilliant medical investigator, Dr. Thorndyke, solves murderous crimes. Percival Bland was an uncommon criminal. He knew that his continual passing of counterfeit banknotes would eventually catch up with him, so he had a plan--precautions against the inevitable catastrophe.

We can understand why he has created an alternate persona, Robert Lindsay, using disguises and renting two places of residence.

No one seems to notice that he and his ""cousin"" Robert never are at their respective homes simultaneously, nor are they at home when the other visits, nor does anyone see the resemblance of their facial appearance under the makeup.

But why does he buy human bones at auction? The lot was described in the catalog as ""a complete set of human osteology"" but they were not an ordinary ""student's set,"" for the bones of the hands and feet...