This is a limit of the QuickBooks interface. We're not able to match the names exactly during the posting, only the beginning characters. In order to work around this, you'll need to make the name of the well Kell distinctly different from Kellering #1. Or, you might want to consider putting #1 in front of Kellering so it appears as '#1 Kellering' instead. This will only happen when the entire name is included in another well's name.
I would recommend changing the names of those royalty owners in QuickBooks since you will now be paying them directly from our software. This will make the name that already appears in QuickBooks different than the name that SherWare is trying to add, so it shouldn't complain about the 3100 error after making that change and synchronizing it again.