THE ADVENTURE OF THE STOCKBROKER'S CLERK by Sir Arthur Conan Doyle

Pycroft is a stockbroker's clerk who had then been taken on by the firm of Mawson and Williams in the City of London. Tthe firm took him on without a face-to-face interview, with arrangements made via the postal system. The job is a good one, and the wages offered more than reasonable.
He also receives another job offer, when Arthur Pinnar, of the Franco-Midland Hardware Company visits him in person. The Franco-Midland Hardware Company has nothing to do with stockbroking, and deals with hardware stores on the continent, but the terms of employment are better than those offered by Mawson and Williams. So despite the job being in Birmingham rather than London, Pycroft accepts the new job offer.
Quickly though, things don't feel right to Pycroft; and the fact that Arthur Pinnar asks Pycroft not to resign from Mawson and Williams, stating that an argument had left ill-feeling between the two company's.
In Birmingham, things are also not what Pycroft expected. The offices are dusty and unsuitable for the expected work, and the work given to Pycroft by Harry Pinnar, Arthur's brother, is meaningless. Pycroft then discovers that Arthur Pinnar and Harry Pinnar are the same person...

First published in the Strand Magazine, Mar. 1893, with 7 illustrations by Sidney Paget.