McCain lasted one season in Miami after a big year with the Steelers in 2014 helped him land $3 million in guarantees from the Dolphins on the open market.
McCain, 29, was due to make $2.5 million in 2016. He finished 2015 with one interception, 10 pass breakups and 31 tackles in 11 starts.
Coples was claimed off waivers from the Jets last November. He played in six games for the Dolphins without recording any stats.
A first-round pick of the Jets in 2012, Coples has 16.5 career sacks but had none last season.