BT AZ 2b(4) :כי היכי דלא ליערבבו אינהי בהדי הדדי, דלישמעו מאי דאמר להו‏ : in such a way that they not become confused with each other, so that they hear what he says to them
See the entire entry for ˁrbb vb. to mix up, confuse