This is something that is not fully supported today by the front end:
https://github.com/DynamoRIO/dynamorio/issues/2384. If you would like to work on this that would be appreciated; please add a note to the issue if so. Note that the scheduler supports mixing multiple processes (as separate "workloads" if different scheduling policies are desired), and we do recommend dynamic rescheduling (see
https://dynamorio.org/sec_drcachesim_sched.html. We will be trying to make that the default rather than the current poor static schedule default). For analyzers, just combining the files into one directory would be a workaround that ignores addressing differences. One way to handle different address spaces if using physical addresses could be via translation files such as support added by recent changes and used in the TLB simulator in
https://github.com/DynamoRIO/dynamorio/pull/6961. Virtual offsets for each workload is another feature that could be added.