Merge pull request matplotlib#29176 from meeseeksmachine/auto-backport-of-pr-29148-on-v3.9.x

Backport PR matplotlib#29148 on branch v3.9.x (Don't fail on equal-but-differently-named cmaps in qt figureoptions.)

Author: timhoffm

lib/matplotlib/backends/qt_editor/figureoptions.py

@@ -149,7 +149,7 @@ def prepare_data(d, init):
     cmaps = [(cmap, name) for name, cmap in sorted(cm._colormaps.items())]
     for label, mappable in labeled_mappables:
         cmap = mappable.get_cmap()
-        if cmap not in cm._colormaps.values():
+        if cmap.name not in cm._colormaps:
             cmaps = [(cmap, cmap.name), *cmaps]
         low, high = mappable.get_clim()
         mappabledata = [