Tested in rc1 and can not reproduce:
grml2usb /live/image /dev/sda1
mkfs.xfs /dev/sda2
xfs_admin -L live-rw /dev/sda2
reboot && select persistent bootoption,
modify something reboot, only one pts entry
Just a cosmetic issue but /dev/pts might get mounted with each persistent boot
and /etc/mtab doesn't get cleaned up so there might be several /dev/pts mount
points in output of "mount".