macOS Catalina renamed external volume name

I have an external APFS RAID 1 array made of three USB hard drives connected to my Mac Mini.

Before I installed Catalina (10.15) on my Mac Mini, this array was called "Primary" and was mounted as /Volumes/Primary/.

After I installed Catalina, that array appears to have disappeared and been replaced with "Primary 1". This is an inconvenience because various programs looked for files in /Volumes/Primary. I can deal with a one-time inconvenience. What's really weird is that "Primary" apparently coexists with "Primary 1". Some applications see "Primary", but others see "Primary 1".

Here's the output from ls -lha@:

ComputerName:Volumes NonAdminUser$ ls -lha@
total 0
drwxr-xr-x   5 root          wheel   160B Oct 31 07:38 .
drwxr-xr-x  22 root          admin   704B Oct 30 20:42 ..
lrwxr-xr-x   1 root          wheel     1B Oct 31 07:31 InternalDrive -> /
d--x--x--x   3 root          wheel    96B Oct 29 07:56 Primary
drwxrwxr-x@ 14 NonAdminUser  staff   448B Oct 31 18:34 Primary 1
    com.apple.backupd.unlockrecordUUIDs   84B 

I should mention that I normally operate my computer as a non-admin user and sign into the admin account for system maintenance and installing new software.

Why are there suddenly two drives, and why do some applications see one path while other applications see another?

EDIT:

Here's the output of df:

Filesystem     512-blocks        Used  Available Capacity iused       ifree %iused  Mounted on
/dev/disk1s5   1953595632    21149624 1183122536     2%  483557  9767494603    0%   /
devfs                 407         407          0   100%     704           0  100%   /dev
/dev/disk1s1   1953595632   709969192 1183122536    38%  609430  9767368730    0%   /System/Volumes/Data
/dev/disk1s4   1953595632    37748824 1183122536     4%      17  9767978143    0%   /private/var/vm
map auto_home           0           0          0   100%       0           0  100%   /System/Volumes/Data/home
/dev/disk6s1  15627315072 10505155688 5120487720    68%  695289 78135880071    0%   /Volumes/Primary 1

This happens from time to time when the dismount isn’t clean. It’s not new and has been around since the beginning of OS X.

Eject the drive and be sure it’s disconnected and then remove the folder where you prefer the volume to mount.

When you reconnect the drive, it will mount in the proper place again.