I bought "Merry Merrily" before this even though this was released earlier. I didn't know they formed a group anyway, and considering they didn't release any more CDs after the two, I don't think it's that important.
It's strange though because they do form a neat pair. It must've been a marketing problem. These two are really interesting even in radio shows and commentaries (Kasimasi DVD). Their conversation tends to be like joke fighting, but in fact they're both digging themselves into holes. When one of them thinks she is losing, she's actually winning, and vice versa.