Have you fixed “dummy” dir permission with the command
sudo chown -R 1000:1000 /path/of/dummy
?
If the problem is different distro use different UID or GID for user and you don’t need to use them with a dual boot machine all you need is to fix the perms of old home directory (and maybe some other few stuff as /var/spool/mail/dummy or something in /var/tmp, etc…) using the new UID/GID pairs in a similar way as following:
sudo chown 1000:1006 -R /your/home/full/path