@Trancos2002
Yes, there is no problem with having two systems running at the same time.
The only thing to keep in mind is that when moving a unit from HCL to HA, you should first exclude them in your HCL.
You can also exclude it in HA, but it will remain in your HCL and be considered a missing unit.
Either way, you must exclude the units or do a manual factory reset of them, otherwise you will not be able to add them (include them) in your new HA system.