As BGR exclusively reported last week, companies will need to run two BlackBerry Enterprise Servers simultaneously if they want to support both BlackBerry 10 devices and older devices that run on BlackBerry 7 and earlier. Jeff Holleran, RIM’s senior director for enterprise product management, provided some key details about the upcoming BES 10 on a company blog post Friday and admitted that companies will need to run both BES 5 and BES 10 to support both old and new devices.

“With the initial launch of BlackBerry Enterprise Service 10, BES 5+ will require its own server, while BlackBerry Device Service and Universal Device Service can reside on separate servers or be combined on the same physical or virtual server,” he wrote. “Should you opt to work with virtual servers, we fully support this type of deployment. Today, BlackBerry Mobile Fusion operates in a similar fashion, with BES 5+ requiring one server, and both BDS and UDS able to be deployed on a single server or on separate servers.”

As BGR noted last week, the requirement to run two servers simultaneously could impose some significant cost requirements on businesses with hundreds or thousands of BlackBerry users, in addition to complications from a deployment and management perspective.