Morton and Eden are re-advertising this DTD. Their entry says:
Dekoratie Voor Trouwe Dienst, 1899-1902, (Burger W.D. Jacobs), extremely fine and rare [591 issued]
Specialist research from South Africa suggests that this medal, while genuine, has been incorrectly machine-engraved rather than officially impressed. Moreover, the type of suspender on this D.T.D. is only found on the third type of A.B.O./D.T.D. issued from 1942, and Burger W.D. Jacobs’ A.B.O. was issued in 1922, before the existence of this type of suspender.
The DTD, as far as I am aware, was also not available to private or non-commissioned ranks - only to officers. Was this not a medal stolen from the SANDF Archives and "dressed up" in order to turn a profit for someone?
I had only started collecting a number of years after the SA version of the Great Train Robbery aka the theft of blank medals from the SANDF. The story, which you and others are probably aware of, is that the enterprising thief also got his (their) hands on the impressing machine and set about naming up a number of WWI-style medals ala 1914/15 Stars/BWM's and VM's, which then "flooded" the market - it stands to reason that they would have stretched this to include ABO's and DTD's.
Perhaps the medal to Jacobs is a product of their efforts to discombobulate and deceive medal collectors in order to turn a profit.