How to run 2 content filters in parrallel?

[Mike Schleif]

CentOS Linux release 7.5.1804 (Core)
mail_version = 2.10.1

Several years funning one content filter:
127.0.0.1:10025  inet  n  -     n       -       -       smtpd
  -o content_filter=filter:dummy
 ...

Now, we need an autoresponder for one incoming address. Trying to use this:
https://www.howtoforge.com/how-to-set-up-a-postfix-autoresponder-with-autoresponse

Tried adding second line to above:
127.0.0.1:10025  inet  n  -     n       -       -       smtpd
  -o content_filter=filter:dummy
  -o content_filter=autoresponder:dummy
 ...

Which always results in this:
 ... status=bounced (User unknown in virtual alias table)


We need _both_ content filters to run on original, unfiltered messages.
There is no dependency one filter to the other.

What am I missing?

Please, advise. thank you.

~ Mike