Comma separated list is a known DB type since opendkm 1.2, so you can work around this issue by forcing it. Try:
PeerList csl:199.192.231.53,2605:eb00:100:1::2085:29b0 -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
