All other enemies (sans Gremlins) have single entries with annotations describing the differences shown by the enemies in different tiers.
Is there any particular reason why Blast Cubes get three separate entries instead of just a single, "Blast Cube" entry?
Those are just Tier 1, 2 & 3 versions of the Blast Cube. Probably nobody has gotten around to changing it since the tier versions were instituted. Feel free to edit it and correct that.