A two-family home, what some markets call a duplex, is financed the same way as a single-family home in Saskatchewan as long as the buyer will occupy part of it, with the same CMHC down payment tiers applying rather than a separate limit tied to property type.
Where a two-family home does differ is income qualification. A lender can count a documented, legal portion of the rental income from the second unit toward qualifying for the mortgage, provided the City of Saskatoon has a permit on file confirming that unit is a legal secondary suite rather than an unpermitted conversion.
That permit status, not a loan limit that does not exist here, is the real threshold to clear. Get your hand-reviewed valuation from Joel Dyck.