There is no need for both - if you have latest Patches fixes for both - like GSE701P1RU2 and GSE702P1 - install the one set of extensions from either of those packages - same policies can be applied for both versions on the Exchange servers.
With all due respect, I don't think tonyharding's question has been answered, as I think I have a similar situation: please forgive me if I've missed something here, however.
I am running both Exchange 2003 and 2010 in my Organisation and want to deploy and manage the two different versions of Groupshield from EpO 4.6.
Currently, GS7.0.1 (and its various patches and management extensions etc) is checked into the current branch in the software repository - which is deployed to the Exchange 2003 servers.
When I went to check in GS7.0.2 - with a view to deploying that for the Exchange 2010 servers - EpO will check it in, however warns me that GS7.0.1 will be moved to the previous branch.
So, I guess the question is: is it best practise to check in GS7.0.2 to the current branch and therefore force GS7.0.1 to the previous branch and still be able to deploy and administer both versions from EpO?
(I have a similar situation with McAfee Agents 4.0.0 and 4.6.0 - 4.6.0 is in the current branch and 4.0.0 (for W2K servers) is in the previous branch, however they are both available to install.)
What I meant is that one GSE Product extension can manage both GSE701 and GSE702 products on E2003 and E2010.
I think you are trying to check to the two packages into the repository - inwhich case one can reside is current branch and one can reside in another Branch.
If you have already deployed the product(s) to your set of servers there is no absolute need for the product(s) to remain in current..