Some DNS providers allow multiple TXT records with the same name but each having a different value. I was just trying to say there are different methods depending on the DNS provider and interface or its api. In any case, with two domains you will need two TXT values.
If you omit the -d betafox.com from the command it will only need one value but the cert will not cover that exact name - only names matching the wildcard.
See this thread for some helpful tips.