I could be wrong but Ive known that to be called poly-spill or Polyphony Spillover.

I have known MIDI overflow to be something entirely different whereby usually a bandwidth bottlenecking occurs on any one particular device, typically like when a large system exclusive change(s) message is going thru that device to another one later in the chain and the amount of bandwidth exceeds the capacity of the thru devices port. The overflow causes whatever data that went over the limit to be ignored.
Hell i dont know these days....um i'm claiming ronny reagen on this one.