When preparing the domain for Exchange 2013, can we use the same Organizational Name as was used for Exchange 2010 or should we select a new variation?

You can use the same Organization name.  Just make sure you have Exchange 2010 at Sp3 at a minimum

When preparing the domain for Exchange 2013, can we use the same Organizational Name as was used for Exchange 2010 or should we select a new variation?

You dont have define the org name since it already exists. 

You can only have one Org in a single forest/domain.

When you run setup /p it will check if there's an existing Exchange Org in the environment. If yes, continue else reply with an error to put in the /on switch.

• Edited by Michael Vi 9 hours 31 minutes ago additional info