Can an integrated circuit package contain more than one die?
Yes, they can include more than one die. This is called an MCM, or Multi-Chip Module.

A common example is eMMC Flash, which includes a bare NAND device coupled with a controller on the same BGA package.

Some high density DRAM and flash devices will use ‘stacked die’, with the upper die made slightly smaller to allow wire-bond to the substrate.

Bigger examples of MCMs include multi-core CPUs like some versions of Intel Xeon and AMD Epyc.

Some FPGAs use stacked die approach to achieve even higher density than is possible with a single die.

More about MCM technology here: https://www.mccoycomponents.com/blog/view/understanding-chiplet-in-one-article



And it's here we learn a shiny-new marketing technobabble word: chiplet. Which is basically a chip, designed to be connected to other chips (excuse me, other chiplets) on the same substrate in Lego-like fashion to make an even bigger chip. Which is still an MCM, thank goodness.

And here I was, up until some minutes ago, thinking chiplets were the leftover broken pieces in the bottom of tortilla chip bowl. You know, those pesky little doodads too small to hold the salsa picante, but still edible if you're desperate.