Quote: 1973 D LMC. Is this Die clash or something else?
I believe its thought to be something else. Quote from Mike Diamonds Coin World article. See link that follows. Note image links seem broken.
Quote: I can only surmise that this is a recurring die subsidence or soft die error (the two error types are closely related and can converge in appearance). While die deformation errors of this sort are usually restricted to a single die, they will sometimes affect multiple dies when there is a fundamental flaw in the die steel or when there is a repeated misstep in die preparation (annealing, tempering, quenching).