Question : FQDN for new domain tree

I have a windows 2003 domain. I’ve upgrade the schema to win2008 mixed. Im adding a win2008 R2 DC to the domain as a new domain tree; thus, making my existing domain a root domain.
I want to name the new domain tree (FQDN)  badapple.com; However, I already have a DNS zone called badapple.com in my root domain. What impact if any will happen if I name this new tree badapple.com. How will it impact the DNS in the root domain?  

Answer : FQDN for new domain tree

oh ok so in that scenario no issues, badapple.com and applesauce.com can exist in the same forest.

The execs would still see all the domains in the dropdown/login screen.

Thanks

Mike