38 Special typify the alternating and shared lead vocals roll, with keys player Bobby Capps getting the odd lead bit too

Sister Hazel - Andrew Copeland gets the odd lead vocal and also recorded his own album, with regular singer Ken Block singing the harmonies for him

Sad Cafe - Paul Young recorded all the lead vocals, but seeing them these recently, 4 people share lead vocals and they are excellent singers

Foreigner - Mick's "Star Rider"

and I recall some band called The Beatles having a go at it too