When you put the SSD in, you installed the OS onto it as a "standalone" (that is, not "fused") drive, is this correct?
And the 128gb SSD is currently "just there" and not being used?
Is this also correct?
In that case, you could erase it and use it, too, as a "standalone" drive.
In other words, TWO drive icons on the desktop, instead of one (no problem with that).
What I'd suggest is that you install a fresh copy of the OS onto the SSD, so that it becomes "a second, bootable drive" that will be "there if you ever need it". It's always a good idea to keep a second bootable drive "close by" for "moments of need".
Hmmmm....
One other thing.
I suggest you use Blackmagic Speed Test (or another disk-speed measuring app) to TEST the speeds on both SSDs (Apple and 3rd party).
I suspect you may find the Apple SSD to be faster...
