Error when trying to add 2nd controller via bluetooth

[digital]

Hello,

I've built a new RetroPie. It's using the Pi3 board, a SanDisk 32GB card and I'm running RetroPie 4.3 downloaded from the site.
I was able to pair a 8Bitdo SFC30 controller via bluetooth.
I have a 8Bitdo SNES30 controller that I'd like to have connected as well for 2 player games. However, when I try to add it, I get an error message, "An error occurred connecting to the bluetooth device (Creating device failed: org.bluez.Error.AlreadyExists: Already Exists)"

The really strange part is, when I look in registered devices/active connections, it shows the mac address of the SNES as active! I know that's not the case because the SNES30 is off, the SFC30 is on and I can navigate and play games with it! I have no idea what is going on or how to fix it.

Resolution steps attempted:

1. Connect PS3 via USB to Pi.
2. Turn off SFC30 and SNES30.
3. Remove all bluetooth devices except the SFC30.
4. Reboot the Pi.
5. Attempt to add the controller via steps outlined here https://retropie.org.uk/docs/8Bitdo-Controller/.
6. Error is displayed.

Notes:

• All controllers are running the latest firmware.
• The closest post I could find was this, https://retropie.org.uk/forum/topic/12739/unable-to-add-second-8bitdo-snes30-controller.
• /opt/retropie/configs/all/retroarch/autoconfig contains 2 files, "Sony PLAYSTATION(R)3 Controller.cfg" (https://pastebin.com/Sd3HBgcN) and "8Bitdo NES30 Pro.cfg" (https://pastebin.com/4iRSVV6i).
• /etc/udev/rules.d/ has "99-bluetooth.rules" (https://pastebin.com/ZpmyPNmP) and "99-bluetooth.rules.bak" (https://pastebin.com/ENFhYSyT).

Pictures:

1. https://i.imgur.com/5paq38H.jpg (when trying to add SNES30 controller - note mac addresses)
2. https://i.imgur.com/kTg4FlU.jpg (error message when tring to add)
3. https://i.imgur.com/YpY8vLY.jpg (registered devices. active is showing 8Bitdo NES30 Pro but it's powered off!)

Details of build:
Pi Model or other hardware: 3
Power Supply used: https://www.amazon.com/gp/product/B01N336XEU
RetroPie Version Used: 4.3
Built From: https://github.com/RetroPie/RetroPie-Setup/releases/download/4.3/retropie-4.3-rpi2_rpi3.img.gz
USB Devices connected: None
Controller connected: https://www.amazon.com/gp/product/B072Q21BD7/
Error messages received: "An error occurred connecting to the bluetooth device (Creating device failed: org.bluez.Error.AlreadyExists: Already Exists)"
Log found in /dev/shm/runcommand.log (if relevant): N/A
Guide used:
File: N/A
Emulator: N/A
Attachment of config files: N/A
How to replicate the problem: Outlined above.

[digital]

I guess dual bluetooth controllers of differing makes/models are not supported?