Hello,
It's all up to you and what hardware do you have avallable to match the 
original, one thing for sure, you cannot use the same host id on the same 
subnet in test, otherwise your enablers on one server will get disabled.
some other things to consider.
Utilizing VTL to emulate the real lib 
Creating seperate vlan or test lab to emulate the production.
I dont belive you  need to duplicate everything, i.e i see no need to 
duplicate every client, the other thing is you can always use production 
Networker server during off peak hrs to do client testing, scripts etc.
I do see a need for somewhat like enviroment to prod for testing version 
updated, driver updates, changes in firmware, drastic changes in backup 
routines, procedures and migration.
The larger problem may be to keep the software licenced, you will need to 
purchanse some permanent licences in order to keep the enviroment stable, 
otherwise rebuilding servers may be nessary to keep the trail version 
going.
HTH

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