Congratulations for noticing this detail. In my version I thought it appropriate to "correct" this behavior of the original game by preventing overlapping enemies that could make the player believe that there is only one.
An excellent idea that I heartily applaud; a great touch. : ) Also I noticed the little musical piece that plays when the player character enters round 1 in your game is slightly different and more jingly than the original arcade version (or at least, the version of that one on PS4)--very subtle but again a nice difference. : )