Piggyback chips was a common technique in the 1970s and early 1980s, in the days when through hole dual inline packgaging (DIPs) were used. A classic example was the first version of the IBM PC-AT, whuch came with "128Kbit" DRAMs, actually two 64Kbit DRAMS in one 16 pin socket.

I had an occasion to do the same thing. Erasing UV EPROMS was time consuming, so I piggybacked two low density 4Kbit EEPROMs to make fast programmable 2708s (8Kbit) replacements for prototyping with early 8048s and 8051s using external memory.
Jack Peacock