No, it's a sophisticaed fencing.
Basically No one is describing this scenario:
ChewA has Mechanical heart, but ChewB wants that item. Mur also has Mechanical heart (MH). So Chew makes a deal with Mur so that Mur passes his MH to ChewB, to compensete for Mur's loss of MH, ChewA will pass his MH to Mur.
Mur still has MH, ChewA doesn't have MH but ChewB now has MH.
Alt abuse can't be detected because MH that ChewA had isn't same as the one that ChewB got, due to different item ID which is used for tracking in logs.
So yes, as far as I see it, No one is right to be concerned.