Cutting a bar magnet in half produces two magnets rather than two monopoles because:

1. A cut magnet is the classic test for monopoles. 2. Isolated north and south magnetic poles are called magnetic monopoles. 3. It is impossible to separate north and south poles the way charges are separated. 4. Magnetic monopoles are not observed. 5. So each half of a cut magnet has both a north and a south pole. _Source: OpenStax College Physics for AP Courses 2e (CC BY 4.0), Ch 22 'Magnetism', sections 22.1-22.11_