CAP 804 in the explanations:
Multi-pilot aircraft
For aeroplanes, it means aeroplanes certi cated for operation with a minimum crew of at least two pilots;
For helicopters, airships and powered-lift aircraft, it means the type of aircraft which is required to be operated with a co-pilot as speci ed in the flight manual or by the air operator certi cate or equivalent document.
And i guess we donīt need to discuss that a CPL-holder can only fly Single-Pilot helicopters as PIC, right?
Just in Case: Cap804, Requirements before you can get a multi-pilot helicopter type rating :Section 4 Part H, Subpart 2 Page 3
(a) Multi-pilot helicopters. An applicant for the rst type rating course for a multi-pilot helicopter type shall:
(1) have at least 70 hours as PIC on helicopters;
(2) except when the type rating course is combined with an MCC course:
(i) hold a certi cate of satisfactory completion of an MCC course in helicopters; or
(ii) have at least 500 hours as a pilot on multi-pilot aeroplanes; or
(iii) have at least 500 hours as a pilot in multi-pilot operations on multi-engine helicopters;
(3) have passed the ATPL(H) theoretical knowledge examinations.