Complex sentence: According to his singing partner Bill Medley, they had agreed to do one solo piece each per album, and both wanted to do "Unchained Melody" for their fourth album, and Hatfield won the coin-toss.
Split into simpler sentences: According to his singing partner Bill Medley, they had agreed to do one solo piece each per album. Both wanted to do "Unchained Melody" for their fourth album, but Hatfield won the coin-toss.