Yes, there is a max jobs per policy attribute. If you select the policy from the list of policies and the choose change, it will take you to the policy attributes. On the left hand side of the policy attributes window about halfway down, there is a check box labeled "Limit jobs per policy". Mark the check box and then using the drop down field underneath it shoose the number of jobs you would like the limit to be.
Hope this helps.
If you have duplicate policies that run at the same time, are they backing up the same clients and filesystems, etc. If so why do you need two. If only one is needed then get rid of the duplicate.