PR 2100 hard drive problem

unfortunately after 1 week of using brand new WD RE 4TB drives . one of them got defected luckily the drivers were in RAID 1 array. can I replace the driver with another type but not same grade (RE) with same capacity and cash level

Mixed hard drives are not recommended for RAID volumes in general. They are a lot more likely to become unstable and drop the array.

If I use red pro with 128 MB cash and RE 64 MB cash both are 4 TB with 7200 RPM can I do that