Use qualified name as ElementPathKey element name to ensure uniqueness

There might be multiple linkable metrics available for a given metric_name + entity_links combo. This is because there might be multiple options for entity paths in the metric subquery, which is not accounted for here. Using the qualified name ensures we will have a unique ElementPathKey for each LinkableMetric.

metricflow/model/semantics/linkable_spec_resolver.py

@@ -120,8 +120,23 @@ def element_name(self) -> str:  # noqa: D102
         return self.reference.element_name
 
     @property
-    def path_key(self) -> ElementPathKey:  # noqa: D102
-        return ElementPathKey(element_name=self.element_name, entity_links=self.join_path.entity_links)
+    def path_key(self) -> ElementPathKey:
+        """Key that can uniquely identify an element and the joins used to realize the element.
+
+        Use qualified name to guarantee uniqueness.
+        """
+        return ElementPathKey(
+            element_name=self.as_group_by_metric_spec.qualified_name, entity_links=self.join_path.entity_links
+        )
+
+    @property
+    def as_group_by_metric_spec(self) -> GroupByMetricSpec:
+        """Convert LinkableMetric to GroupByMetricSpec."""
+        return GroupByMetricSpec(
+            element_name=self.element_name,
+            entity_links=self.join_path.entity_links,
+            metric_subquery_entity_links=self.metric_subquery_entity_links,
+        )
 
     @property
     def reference(self) -> MetricReference:  # noqa: D102
@@ -257,7 +272,9 @@ def intersection_by_path_key(linkable_element_sets: Sequence[LinkableElementSet]
                 for path_key, entities in join_path_to_linkable_entities.items()
             },
             path_key_to_linkable_metrics={
-                path_key: tuple(sorted(metrics, key=lambda linkable_metric: linkable_metric.element_name))
+                path_key: tuple(
+                    sorted(metrics, key=lambda linkable_metric: linkable_metric.as_group_by_metric_spec.qualified_name)
+                )
                 for path_key, metrics in join_path_to_linkable_metrics.items()
             },
         )
@@ -355,11 +372,7 @@ def as_spec_set(self) -> LinkableSpecSet:  # noqa: D102
                 for path_key in self.path_key_to_linkable_entities
             ),
             group_by_metric_specs=tuple(
-                GroupByMetricSpec(
-                    element_name=linkable_metric.element_name,
-                    entity_links=linkable_metric.join_path.entity_links,
-                    metric_subquery_entity_links=linkable_metric.metric_subquery_entity_links,
-                )
+                linkable_metric.as_group_by_metric_spec
                 for linkable_metrics in self.path_key_to_linkable_metrics.values()
                 for linkable_metric in linkable_metrics
             ),