Don't change constant names in FunctionGraph features

pytensor/graph/features.py

@@ -753,7 +753,8 @@ class PreserveVariableAttributes(Feature):
     """
 
     def on_change_input(self, fgraph, node, i, r, new_r, reason=None):
-        if r.name is not None and new_r.name is None:
+        # Don't change the name of constants
+        if r.owner and r.name is not None and new_r.name is None:
             new_r.name = r.name
         if (
             getattr(r.tag, "nan_guard_mode_check", False)

pytensor/graph/rewriting/basic.py

@@ -588,10 +588,6 @@ class MergeFeature(Feature):
         sig = c.merge_signature()
         other_c = self.atomic_sig_inv.get(sig, None)
         if other_c is not None:
-            # multiple names will clobber each other..
-            # we adopt convention to keep the last name
-            if c.name:
-                other_c.name = c.name
             self.scheduled.append([[(c, other_c, "merge")]])
         else:
             # this is a new constant