Yes, leave it there. Saw the same thing when I swapped out the units in my W124. The OEM unit still had it in place, so I left it alone.

Perhaps someone knows exactly why it's there? Or is this along the same lines as mattress tags?

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car