Nicknamed the "Copycat Clone Club" by Angela, they are the best and possibly only friends of Nanette Manoir, the main antagonist. But they are treated more like her servants who follow Nanette around wherever she goes.
January is African American while Karlene is White. The two of them sport bouffant hairdos, preppy clothing and beauty moles, they are very concerned with their appearance and look to Nanette for fashion guidance (mainly about facials and makeup). When Nanette makes a statement, January instantly agrees and then Karlene agrees "even more."
Despite their devotion to Nanette they aren't shown to be loyal to her. An example of this was when Nanette was bedridden with a head cold, they found themselves without a leader and instantly latched onto Angela (the protagonist of the show), who had the high-status job of organizing the school’s spring fling decorations. However, once Nanette got over her cold, they came back to their leader at the drop of a dime.
Nanette and January actually had a falling-out with Karlene in one episode just because Karlene's very rich father cut her allowance by a large amount when he found out she used his credit card to buy "ceramic" kitty collectibles for her, making her unable to buy a real fur hat and having to buy a fake one, which resulted in Karlene hanging out with Angela and the rest of her friends. However, it is revealed later in the episode that Karlene was only hanging with them so she could save enough money to buy a real fur hat (since she believed in having fun by spending money, and claiming that she had saved $120 in the time she spent with Angela).
But of course, Angela had the last laugh when Karlene accidently switched hats with Angela leaving her the real one by mistake, while she wore the fake one that she had given to Angela. Angela got her own back by making Karlene make sandwiches for her and her friends as she has promised them beforehand before she gave her hat back.