The question is right to ask about how to do this in practice. Yes, this is done using two beams, but those beams come from the same source:
The electron beam (in a modified electron microscope) is sent through electron optics where it is split in two by a thin wire at negative voltage. After that the beams focused again at the same spot where it produces interference fringes. The electron optics works like a biprism.
In a way it is the same as a demonstration experiment that I show every year with a laser beam that is split in two by reflection from the front and the back of a thick glass plate. Those beams are then two centimeters apart. But when those beams are diverging (because of a lens in front of the laser) they will overlap at a large enough distance, where an interference pattern is then produced. It is is the pattern of interference from two point sources. The data from the electron experiment (shown in Anna V's answer) also look like that. A single-slit envelope pattern is not apparent.
Edit: I just came across this article with 600 eV electrons (50 pm wavelength) and real milled slits:"The individual slits are 62 nm wide and separated by 272 nm."
Bach, Pope, Liou and Batelaan (2013)