Why does smtp-server.pl return the same cert multiple times

[jetmore]

See test _exec-transactions/00200. smtp-server.pl is using the default cert, which is node.example.com.key/.crt

That test runs (more or less):

../../swaks --to [email protected] --from [email protected] --helo hserver   --tls   --pipe '../server/smtp-server.pl --silent --domain pipe   part-0000-connect-standard.txt   part-0101-ehlo-all.txt   part-0200-starttls-basic.txt   part-0101-ehlo-all.txt   part-1000-mail-basic.txt   part-1100-rcpt-basic-accept.txt   part-2500-data-accept-basic.txt   part-3000-shutdown-accept.txt   '

And the peer certs are reported as

=== TLS peer[0]   DN="/C=US/ST=Indiana/O=Swaks Development (node.example.com, with-SAN)/CN=node.example.com/[email protected]"
===               notBefore=2023-11-03T14:50:10Z
===               notAfter=2033-09-11T14:50:10Z
===               subjectAltName=[ DNS:node.example.com ]
===               commonName=node.example.com
=== TLS peer[1]   DN="/C=US/ST=Indiana/O=Swaks Development (node.example.com, with-SAN)/CN=node.example.com/[email protected]"
===               notBefore=2023-11-03T14:50:10Z
===               notAfter=2033-09-11T14:50:10Z
===               subjectAltName=[ DNS:node.example.com ]
===               commonName=node.example.com
=== TLS peer[2]   DN="/C=US/ST=Indiana/O=Swaks Development (node.example.com, with-SAN)/CN=node.example.com/[email protected]"
===               notBefore=2023-11-03T14:50:10Z
===               notAfter=2033-09-11T14:50:10Z
===               subjectAltName=[ DNS:node.example.com ]
===               commonName=node.example.com

When I spin up smtp-server.pl on tcp and hit it with s_client, it also reports the same cert multiple times:

../server/smtp-server.pl --domain inet   part-0000-connect-standard.txt   part-0101-ehlo-all.txt   part-0200-starttls-basic.txt   part-0101-ehlo-all.txt   part-1000-mail-basic.txt   part-1100-rcpt-basic-accept.txt   part-2500-data-accept-basic.txt   part-3000-shutdown-accept.txt

openssl s_client -host 127.0.0.1 -port 11111 -starttls smtp

Connecting to 127.0.0.1
CONNECTED(00000003)
Can't use SSL_get_servername
depth=0 C=US, ST=Indiana, O=Swaks Development (node.example.com, with-SAN), CN=node.example.com, [email protected]
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 C=US, ST=Indiana, O=Swaks Development (node.example.com, with-SAN), CN=node.example.com, [email protected]
verify error:num=21:unable to verify the first certificate
verify return:1
depth=0 C=US, ST=Indiana, O=Swaks Development (node.example.com, with-SAN), CN=node.example.com, [email protected]
verify return:1

Given that, I see this as an issue w/ smtp-server.pl, not with swaks, so I'm creating this issue and dropping it into the backlog. My logic is that swaks is actually correct - as a test tool,, if the peer is returning the same cert 3 times, I want to know that. But my preference is that most tests work as expected (one cert), with only one or two "does it report the same cert multiple times when presented multiple times" tests