It could be another Maeda Atsuko. Sorry for the delay in reply, I was busy, but I looked into it, and the probability that there's another person named Maeda Atsuko is highly probable. First, there're members who share the same romanized/pronounciation of their names, like Ota Riona (NMB48), Chen JiaYing (SNH48 Group), and Yokoyama Yui (AKB48). Second, there're members that share their names with other artists/talents outside of the group, like Takahashi Minami (seiyuu, Sega Hard Girls), Takei Sara (8th gen iDol Street), and Kudo Haruka (ex-Hello Project). Third, as I've mentioned earlier, I looked into it, and found that there's really an another Maeda Atsuko, and this one is from HR, a Hakata-based local idol group (means that they only perform in Hakata), although the Kanji is slightly different (前田温子). With all these three pointers, it's safe to assume (unless Acchan adds it into her portfolio, which currently is not) that the one in He's Such a Girl is a different person sharing the same romanized name.