@embeddedt Thank you very much for your reply.
I was able to get 2 frame buffers to be available in /dev/ with the following configuation in /boot/config.txt
I think the key was commenting out: dtoverlay=vc4-fkms-v3d
hdmi_pixel_encoding:0=2
hdmi_group:0=2
hdmi_mode:0=27
hdmi_ignore_edid:0=0xa5000080
hdmi_pixel_encoding:1=2
hdmi_group:1=2
hdmi_mode:1=27
hdmi_ignore_edid:1=0xa5000080
[all]
#dtoverlay=vc4-fkms-v3d
max_framebuffers=2
gpu_mem=512
Hopefully this will help someone else in the future.
Thanks!