Re: dsPIC33CK256MP508 dual core?
"slave core" like in "slave microcontroller core"?
Could it be you've mistaken the CK family (single microcontroller core) for the CH family (dual core) ?
("core0/1/shared" is just about ADC converter "cores".)
PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)