What I wanted to do is project a very small spot from something like an LED light in a dark chamber into a very small spot, say ~2 microns
No way. In a regular pinhole camera, diffraction sets a minimum spot size on film of order a few 100s microns; same here. Plus two holes in succession will severely limit the light throughput.
To produce a 2 micron spot on film one needs a lens f/4 or faster, free from aberrations at the level of the diffraction limit; a far cry from a pair of pinholes.