diff --git a/klippy/extras/adxl345.py b/klippy/extras/adxl345.py
index c2d64a412..87420d79f 100644
--- a/klippy/extras/adxl345.py
+++ b/klippy/extras/adxl345.py
@@ -114,8 +114,16 @@ class AccelCommandHelper:
         self.name = name_parts[-1]
         self.register_commands(self.name)
         if len(name_parts) == 1:
-            if self.name == "adxl345" or not config.has_section("adxl345"):
+            # Try to register default mux commands for the accelerometer
+            # without explicit name. If default accelerometer has already
+            # been registered, raise an error.
+            try:
                 self.register_commands(None)
+            except config.error:
+                raise config.error(
+                    "Default accelerometer already defined; section '%s' must "
+                    "include an additional name, e.g. '%s second_accelerometer'"
+                    % (self.base_name, self.base_name))
     def register_commands(self, name):
         # Register commands
         gcode = self.printer.lookup_object('gcode')