I wanted to combine 2x sandisk extreme pro portable SSD via a dual bay nvme enclosure, so I did a test and removed 1 sandisk extreme pro SSD from its case/enclosure and insert it into the external enclosure, and using blackmagic disk speed test was only able to get about 170-200 MB/s, but putting the ssd back. into the sandisk portable enclosure, I am getting 950/MBs. why is this happening?

I tested the external enclosure with another nvme SSD was able to get 980/MBS, so it’s not the external nvme enclosure’s issue. just not sure why the sandisk nvme ssd are not getting full speed when using the external enclosure vs sandisk’s own case/enclosure as both of them uses USB C interface and should perform the same.