The older BOINC server code just checked for the version of the driver and not whether CAL and/or OpenCL is supported. For some reason (probably because they could implement it faster), DA decided to make OpenCL a sub-class of ATI rather than a separate coprocessor type. So, if the server sees you have ATI (and you do because the OpenCL has to be reported as an ATI coprocessor) then it sends out ATI work.
The only fix is for Moo to add a check for OpenCL and CAL and figure out which app to send depending on whether the GPU supports one or the other or both.