two people sharing one role
Used in contexts such as theater, film, or work assignments where two actors or workers jointly perform a single role or task.
In this play, two people share the lead role.
In a busy department, sometimes two people share one role and divide the work.
Compound of 二人 (ふたり, 'two people') + 一 (ひと, 'one') + 役 (やく, 'role'). The reading ひとやく follows standard rendaku for 役.