Do I need to un-install Specify 5 to install Specify 6?

No, one does not need to un-install Specify 5 to use Specify 6. Specify 5 uses Microsoft SQL Server, whereas Specify 6 uses MySQL for the back-end data manager. Installations of these two database management systems are independent and will not interfere with one another. The Specify 6 application is also independent of the Specify 5 software and should pose no conflicts. Any existing Specify 5 data need to be migrated to Specify 6 by the Specify Software Project staff. Contact us for details.