fix(helm): replace repo entry instead of duplicating

Closes #1522

pkg/repo/repo.go

@@ -113,15 +113,19 @@ func (r *RepoFile) Add(re ...*Entry) {
 // entry with the same name doesn't exist in the repo file it will add it.
 func (r *RepoFile) Update(re ...*Entry) {
 	for _, target := range re {
+		found := false
 		for j, repo := range r.Repositories {
 			if repo.Name == target.Name {
 				r.Repositories[j] = target
+				found = true
 				break
 			}
 		}
+		if !found {
 			r.Add(target)
 		}
 	}
+}
 
 // Has returns true if the given name is already a repository name.
 func (r *RepoFile) Has(name string) bool {