Resolved duplicate messages from HarnessErrorList section

When using pyCaseErrorSection to call HarnessErrorList and display any errors on Clipboard page, when the Clipboard page had more than one error then the error message was shown multiple times. This has been resolved by adding a check that will iterate through the errors to see if it is present on the page already. If it is present it will be ignored, and if it is not present, then it will be added.