AFAIK and as you have already read in this forum:
.... I have read a few posts that if a License is shared by two machines then the QlikView Server goes off in these both server. ..
the same license can't be used simultaneously in multiple environments (assuming not clustered). Hence, to get back your PROD back, you need to remove the license from the DR and thereafter apply in PROD.
If you want a hot stand-by server, you'll have to buy a second server license. It's as simple as that: a single QlikView Server license may not be used on multiple platforms. Read your license agreement.
Simple solution: turn your Disaster recovery environment into a cold stand-by server, meaning you switch off all QlikView services. You can still distribute documents to both machines or to a shared location, to keep the backup-machine up to date. But you cannot keep it running.
If I'm not mistaken, only the second server (the one that is started last) will go off-duty.
Thank you tresesco and Peter.
When I started my Disaster Recovery Server the production server went off. I remember I have tried to bring the production server on by shutting down all the services in DR server but it did come up.
Nevertheless, I can't test the process now as we are already LIVE for initial testing.
Will do the fixing as suggested and get back if any issues.