Installing a 32-bit and a 64-bit instance of SQL Server 2008 R2

I am setting up a new server and have discovered that one of the applications we are installing will only run on a 32-bit instance of SQL Server. So, my plan is to install both a 64-bit and a 32-bit instance of SQL Server 2008 R2 and have one question regarding best practices. Should I install two separate named instances (e.g. SQL64 and SQL32) or should I install a default instance of the 64-bit version and then a named version of the 32-bit version. Does it make a difference either way?

Thanks in advance.