Trade Bill Import gives "ConQuest has encountered a problem and needs to close"

There is a known issue with the Trade Bill Import where if you have a bill with the same name as the bill you are trying to import, but with a different bill number, the import will fail and ConQuest will close.
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If this is a different bill, change the name of the existing one so that it does not match the Trade Bill. If it is the same bill, change the number to match the Trade Bill