The seventy-two angels acquired, in the seventeenth century, a shadow list. The arrangement associated with Thomas Rudd pairs each angel of the Shem ha-Mephorash with a spirit of the Goetia holding the same position, and states the relation as constraint: the angel binds the demon of that degree.
The scheme only became possible because of an editorial act. The Goetia's ancestor, Weyer's Pseudomonarchia Daemonum, lists sixty-nine spirits. The Lemegeton brought the count to seventy-two by dropping one entry and adding four. Whatever the compiler's reasons, the effect was to make a one-to-one pairing with the angels arithmetically possible for the first time.
The direction of the adjustment is the interesting part. The Shem list is older, is generated by a fixed procedure, and cannot be lengthened or shortened without abandoning the procedure. The demon list is a compilation with no fixed length and a known history of editing. When the two were brought into correspondence, the demon list moved.
Rudd's material is separate from the Lemegeton and is transmitted in its own manuscripts; the Goetia's own text does not name angels. Modern editions that print an angel beside each spirit are combining two seventeenth-century sources.
For the angels, the practical effect of the pairing has been that they are now rarely discussed on their own. A list generated from Exodus by a medieval Jewish technique and turned into an angelology by Renaissance Christian humanists is today most often met as one half of a diagram whose other half is a catalogue of demons descended from a sceptic's exhibit. That is a strange fate for it, and it is worth being aware of it as a fate rather than as the natural state of the material.