Reading already formatted drives

Recently I changed out the drives on my EX4100 unit from 4x2tb spanning to 2x8tb RAID1. I’ve realised that there is information still on the old drives that I need to retrieve, however, when I place the old drives back into the unit it attempts to read them as a RAID1 array and fails to show me the data. I’m wondering if there is a way of telling the EX4100 that it needs to be reading it was a spanning drive not a RAID1 drive?

Data recovery can be the only option in such scenario because spanning mode is for the Performance only and it has no data redundancy at all. Moreover, it spreads the data into parts on all the drives due to which one drive failure can cause the data loss because the portion of that file is being lost in the failed drive.