I think you should be able to find an older version of BBm either on the RIM/Blackberry site or Goog for the last version you had. Hopefully you remember what version it was.
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I just downloaded the 5.0 upgrade, but I liked the bbm on the old version much better. Is there any way to get it back?
Delete it off your phone(but not before you do a back up via email I find best)
Connect phone to DM, click on Aplications where you'll find the option to reinstall the version that came with your last OS.
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