Erasing ? - by: Taurid

Please accept my apologies if this question has been asked and answered before. I have searched for an answer but came up empty.

While searching the net for QSA medals I came across some that were described as "professionally erased". To say I was taken aback is putting it mildly as the medal description indeed described how the name and numbers were taken off.

Is this common, what does it mean exactly and lastly why would anybody do something like this?

Thank you.
Gordon