What were the ModeS hex codes of the two aircraft? Were they similar, in which case this might be another instance of single-bit reception errors causing a mix-up between the DF20 data of two different aircraft.
EDIT: Tracked down the ModeS hex codes:
C00FE2 : 1100 0000 0000 1111 1110 0010
4005E2 : 0100 0000 0000 0101 1110 0010
So, three bits in error needed to cause this. Possible, I suppose.