Okay, if think I have a theory about this story so far and even though this is a guess I'll relay my thoughts has a spoiler.
I really don't think you need to spoiler-mark speculation or guesses. I haven't noticed people doing that much on here, generally the spoiler bars are just used when discussing events or information from a chapter that hasn't landed on Dynasty yet.
Okay, first of all, I think that Maki-sensei and Chie-sensei are also twins (based on the 4th chapter, where Chie suggests to switch with Maki for the date with Ako).
No, you're misunderstanding that scene. She isn't suggesting they switch for a date, she's picked up on the fact that there's something going on, and she's offering to take her place in giving Ako remedial lessons. She's trying to save Maki from getting into a dangerous situation. That scene is -after- the date, anyway, and they hadn't made a second one yet.
Which leads to my second theory that Ako has actually run into Chie-sensei (disguised as Maki-sensei) at the end of chapter 5 and Chie is the one inviting her to her apartment (probably trying to ruin their relationship which is a bit opposite to Komachi's approach).
I'm pretty sure Maki is inviting Ako to her apartment because she intends to bang her.
She didn't trim her fingernails for no reason. (and Chie definitely noticed that, with the way she was staring Maki's hands the next day.)
So basically we have two pairs of twins that although have different personalities, their relationship with their sibling is very parallel to each other. In the case of Ako, she feels inferior in her looks compared to her sister. While Komachi feels that she and her sister are the same and will be together because of that.
In the case of Maki-sensei and Chie-sensei, although, it isn't totally clear, I think that when they were teens, Maki enforced her principles onto Chie and it felt to Chie that she was being forced to be similar to Maki causing a rift between them and becoming distant with each other (in the 2nd chapter it is implied that Chie and Maki were not together during their university years), but Chie seems to have feelings for Maki and is trying to get back together with her, hence she is trying to sabotage Maki's and Ako's relationship.
I'm really pretty certain Maki and Chie aren't related. They went to high school together, but they didn't look alike at the time, and there's no in-story indication that they look similar. Even if their hair was different, the students would have picked up on the similarity and commented on it. Chie wouldn't be the legendary volleyball teacher, She and Maki would be the legendary teacher twins. On top of that, they have different surnames.