systemd also listening on imaps port

I noticed that most of the time with dovecot 2.3 I get this output, showing systemd listening on the port as well:

lsof -i TCP:993 systemd 1 root 38u IPv4 3388360574 0t0 TCP *:imaps (LISTEN) systemd 1 root 41u IPv6 3388360575 0t0 TCP *:imaps (LISTEN) dovecot 11607 root 5u IPv4 3388360574 0t0 TCP *:imaps (LISTEN) dovecot 11607 root 6r IPv6 3388360575 0t0 TCP *:imaps (LISTEN)

Sometimes I don't get the extra systemd lines, but I can't reproduce it now. It's only for port 143 and 993. Other ports show only two dovecot processes. Operation seems to be normal.

Is this how it is supposed to be with dovecot 2.3? This is Ubuntu 16.04.