Hey Cindy! This is Michael on the Moz Help Team! You can absolutely set up a second idential campaign with different competitors for prupose of tracking 6. This is actually the recommend workaround for our campaign limitation of tracking 3 competitors. Keep in mind that the 2 campaigns will most likely not update at the same exact time, but if you remember the day of the week that you setup the origianl campaign, you'll want setup the second campaign on the same day to keep their data gathering in sync.
I hope this helps! If you need more details guidance on moving forward with this option in your account, feel free to reach out to us at help@moz.com. Our Q&A forum is a great place to get some quality answers to your queries, but help tickets can help ensure the privacy of your account details. 
Cheers!
To see the source of those errors, you’ll need to export your full Crawl Diagnostics CSV, which you can do by clicking the "Email CSV" button at the bottom of the issues overview. Once the report generates, it will be emailed to you and you will want to open it up in something like Excel. In the first column, perform a search for the URL of the page you are looking for. When you find the correct row, look in the column labeled Referrer (column AM). This tells you the referral URL of the page where our crawlers first found the target URL. You can then visit this URL to find where we linked to that page.