Running UNZIPJCL from the pax file, a number of data sets are created with a name like "myhlq.CAI.CAS9E10.F1". I've also noticed that running the RECEIVE job creates a duplicate of that data set, with the name "myhlq.CAS9E10.F1". So while the data set names are slightly different the contents are identical.
Should I avoid the duplication by modifying the UNZIPJCL DSN's by removing the "CAI." ?
No, the data set names created by the UNZIPJCL job must contain the "CAI" as the second qualifier. This is because the SMPMCS is built with RFDSNPFX(CAI) specified and this value gets appended to RFPREFIX(DASDHLQ) which is specified in the RECEIVE job.
The RELFILES created from the UNZIPJCL job (with the "CAI" qualifier) are identical to the RELFILES that are created when the RECEIVE job is run. This is normal and expected. This is the way Electronic Software Delivery (ESD) is packaged to work with SMP/E. I guess you need to think of the old days when tapes/cartridges were shipped containing the software. On the tape would have been the RELFILES with the "CAI" qualifier, and the SMP/E RECEIVE job would have created the RELFILES on DASD as you are accustomed. The only difference with ESD is that the RELFILES that used to be on tape are now created on DASD.
Finally, while the RELFILES created by the RECEIVE will automatically get deleted when the function is ACCEPTED...the RELFILES created from the UNZIPJCL job need to be manually deleted after the install is complete.