Many of you noticed the somewhat messy performance that the chosen members from Kara, 4minute and T-ara put up earlier this evening on the 14th August episode of Music Bank. In a nutshell, Seung Yeon (Kara), Hyuna, Ji Yoon (4minute), Hyo Min, So Yeon (T-ara) were the 5 chosen ones that did Chae Yeon's Two of Us performance.
Most of you deduced that they didn't have much practise since it was so messy and it must be a last minute thing. But in a clip released of them in the studios rehearsing to Two of Us, there was some mistakes, but it looked more solid. Just too bad, it didn't translate to the performance on Music Bank. The second part of the clip is Chae Yeon's rehearsal for her song, Fool. Enjoy the performance that wasn't to be.
For comparison, the performance at KBS Music Bank.
IMO, Hyunah was a lot better in this, but what's up with her and Soyeon. I'll go ahead and say that netizens will be claiming "feud!" in no time.
Source:AllKPop w/decent commentary