You processed and committed NetCommunity transactions into a batch in The Raiser's Edge. The gifts are on the RE contact records. You notice in the NetCommunity Plugin, the original transactions showed back up as a duplicate.
If you are not fully hosted by Blackbaud, ensure your Raiser's Edge and Raiser's Edge Web Service are on the most recent versions. The product versions can be check by going to your configuration page.
The most recent versions can be found on downloads.blackbaud.com.
If you are on the most recent versions and you confirm the transaction in the plugin is a true duplicate, it can be deleted out of the plugin.