You will need to check for one issuer then fallback to the other issuer if the first check doesn't pass. You will not be able to do an "OR" statement in the issuer.
You can use a regex if you would like. The following is from the online help for the Machine Cert Action.
Specifies a regular expression to use to match the Issuer content against the specified pattern.
The order of RDNs is the same as is displayed; the required separator is a comma ,.
Example 3. Regex extraction
Partial match. CN=.*, OU=FP, O=F5, L=San Jose, S=CA, C=US
Exact match. E=test@f5.com, CN=f5clientrootcert, OU=es, O=f5, L=london, S=chertsey, C=uk
You could have something like
CN=CA.*, DC=ABC, DC=COM
and that should match
CA1
and
CA2
.
-Seth