I always considered Melodica as a single when it came out. The 2 * 12” was, like most doubles back then, for mixing. Most if the tracks on the second 12 were instrumentals so that you could easily mix with the same track.
Nia was definitely presented as an album, that just wasn’t loud enough for mixing with, too many tracks.
The A to G ep was more album like, in that it was all different songs over 2 12’s but was labelled as an ep and pressed loud.