Sounds like it needs to be paired. I lost a key and had to go to the stealer to get a new one. Key from the parts counter only worked like your "less beat up key" had to go to the service counter for them to pair it. Took 5 min, should be done for free.

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1999 323i vert
2004 325xi
2006 X5 3.0
2018 Giulia Ti Sport