Recombine two volumes on an external SSD

I was given a Crucial MX500 SSD. I want to put it in an external case and use it for a backup.

When I mount the drive, I see two volumes "Untitled" (1.08 GB) and "UNTITLED" (498GB)

Disk Utility sees them as separate disks, I can't combine them.

When I looked at them in the system information, I see that the smaller disk has an MS-DOS FAT32 system in it. (I guess it had been used in a Windows system.)

Does anyone know how to recombine the two "disks" into one?

I'm okay with using terminal, if that's what it takes.

Thanks for your help.