different Cert for POP/IMAP

[mno]

Hi List, 

I'm using cyrus with IMAPs and POP3s and would like to use different
certificates 
Looking at the default imap.conf file I have different parameters for a
global certificate
As well as individual params for Cert/keys for IMAP/ POPs etc. 

When configuring the individual parameter pop3_tls_cert_file and
pop3_tls_key_file it seems these params are ignord.
Looking at the manpage (man imapd.conf) are not mentioned. 
Though I' not a programmer, I had a look at the source itself and did not
find any hint for the 
Use of pop3_tls_cert_file and pop3_tls_key_file. 
These params are useless - can anybody confirm this? 
How can I use different Certificates for pop and imap ? 

BR MNO