HI wstahn,
Does your jobs use same selection list?
If there are multiple Jobs using same selection list, then updating the priority of one backup job will cause the priority for other backup jobs to be changed as well. in
Document ID: 309309.
http://support.veritas.com/docs/309309
Check the document, maybe it help.
Another way, is to know how long the jobs takes, then only start the next job when the last finnish.
Regards,
JoaoMatos