Side-by-side shotguns are generally not considered as competition shotguns. They are widely used in bird hunting, field and big game hunting events. yet this is just a personal preference. They can very well be used in sporting clays as well.
SIDE-BY-SIDES:
Marila
Penelope
Ferina
Crecca
Vezir
Hola
I myself know many people who are good at competition events such as trap shooting, skeet shooting, clay pigeon shooting activities with side-by-side shotguns as well as bird hunting.
 
BirdnClay Shotguns