enum MyEnum {
    case one
    case two
    case three(user: String)

    func isOfSameType(_ other: MyEnum) -> Bool {
        switch (self, other) {
        case (.one, .one):
            return true
        case (.two, .two):
            return true
        case (.three, .three):
            return true
        default:
            return false
        }
    }
}

var array: [MyEnum] = []
func add(_ value: MyEnum) {
    if array.contains(where: { value.isOfSameType($0) }) { return }
    array.append(value)
}

add(.one)
print(array)
add(.two)
print(array)
add(.three(user: "Carl"))
print(array)
add(.three(user: "Junior"))
print(array)