promql/value.go
func (m Matrix) ContainsSameLabelset() bool {
	l := make(map[uint64]struct{}, len(m))
	for _, ss := range m {
		hash := ss.Metric.Hash()
		if _, ok := l[hash]; ok {
			return true
		}
		l[hash] = struct{}{}
	}
	return false
}
func (m Matrix) ContainsSameLabelset() bool {
	l := make(map[uint64]struct{}, len(m))
	for _, ss := range m {
		hash := ss.Metric.Hash()
		if _, ok := l[hash]; ok {
			return true
		}
		l[hash] = struct{}{}
	}
	return false
}
// ContainsSameLabelset checks if a matrix has samples with the same labelset
// Such a behavior is semantically undefined
// https://github.com/prometheus/prometheus/issues/4562