Hi,
There are two different scenarios:
1. Planned Migration - the original VMs at the primary site are being shutdown and only then are being powered on at the recovery site.
2. Disaster Recovery (your scenario) - yes, after the primary site is up and running again, there will be IP conflicts. SRM has no way to prevent this from happening. It will no perform any changes to the primary site until instructed to do so (i.e. performing a reprotect).
You have several ways to overcome:
1. Once you performed DR, ensure primary site is isolated from networking perspective to avoid IP conflicts.
2. Manually shutdown VMs at primary site when it becomes available.
3. Run a Planned Migration when primary site becomes available. This will shutdown VMs and perform cleanup at the primary site.
Michael.