[lproven]

There are two projects which did that.

If you were running Windows NT, when running a 16-bit .EXE file, there was a checkbox in the properties dialogue titled something like "run in separate memory space". That launched this particular binary in its own isolated wow16 runtime.

Of course, being an official Microsoft Project slightly reduces how impressive visit.

The other one that I am aware of is that Quarterdeck's DESQview/X could run multiple instances of Windows 3.1 in standard mode in separate windows under a single instance of DESQview.

[signaru]

Could what winevdm be doing on 64bit Windows be considered the same? (I find it very interesting but don't know enough to tell if it should be considered an example)

[hollandheese]

That was also how OS/2 2.0+ ran Windows programs.