I think those are temp files too and can be safely deleted. ETA: I meant the ones with names like you mentioned in your original post.
What version of SEP is in use? I would definitely recommend upgrading to the latest. For example, one of the fixes for MR4 (11.0.4000.2295) is:
Temp files left over in the 7.5 folder after scans.
Fix ID: 1405018
Symptom: After a scan, Symantec Endpoint Protection does not clean up all temporary files from the "7.5" folder.
Solution: The heuristic scan engine was incorrectly holding on to the temporary files in the 7.5 folder during the scan. Modified the engine to prevent this issue from occurring.
Thanks,
sandra