https://www.cnbc.com/2017/08/29/amazon-echo-how-to-play-the-same-music-and-songs-in-multiple-rooms.html

Amazon said on Tuesday that its Amazon Echo units can now serve as a multi-room speaker system.

If you own more than one Echo, Echo Dot or Echo Show, you can ask all of them to play the same song in multiple rooms. Or, if you prefer, you can ask each one to play a different one.