Yes and no. There's nothing about the MSI tables that would prevent this. However if you do so, many prerequisites would be likely to fail due to MSI running only a single execute sequence at a time.
But to really answer, why would you want ISInstallPrerequisites in the execute sequence? If it's for silent installations, you need to kick those off through setup.exe or install the prerequisites manually. Is this something that would be better handled by a suite installation?
Once upon a time I wrote a non-traditional bootstrapper using a Basic MSI project. To get around the mutex limitations in Windows Installer ( one execute sequence per machine and one ui sequence per process ) and still meet the spirit of a non-interactive installation experience I did the following:
Per CA's in the UI sequence after the Execute action that created processes to run the chained MSI's in.
Ran the `bootstrapper` with /QR instead of /QB. This processes the UI sequence but skips the authored dialogs. It wasn't perfect but it made everyone happy for 5-6 years ( and counting ).
