The radio that you use for the buddy box doesn't matter what channel it is on. So no, they don't need to be on the same frequency. The channel of the buddy box doesn't matter at all. In fact, on all of the radios that I've converted to be a buddy box I have completely removed the cyrstal. As well as the batteries, with the exception of the JR box which requires a charged battery in the buddy box to work properly.

Ken