1980s arcade video games generally had multiple ROM chips.
I suppose these often mapped into a single address space and often may have been bank switched in and out of sections of a single address space, and often a mix of the two.
Conceptually either should be possible in Ghidra's Memory Map window, using "Overlay" with "File Bytes". Even though I can import a second file into a window that already has a file open, going into the Memory Map, even though there's a dropdown menu for "File Bytes", it's only populated with one file.
Is there some way I haven't been able to find that lets me load two ROMs into a single address space? It's certainly useful for many other scenarios than just old arcade games.