There are a few ways to achieve what you’re after. It sounds like what you need is to separate your users. Whilst groups can definitely achieve this, in order to use a condition (which will make the template appear for the correct user) the key will be the permission that the user or group has been assigned.
You could first group your users into two separate groups (casual users and advanced users) but they would each need to have different permissions associated with the group (i.e. Contract Agent/Manager/Administrator). Then you would create a field match condition in each template that will check what permission the user has. For example in the Casual Users Template the condition would be a field match condition that is True when the User Permission field = Contract Agent.
This condition could then be put on the template and if the user is a member of the Contract Agent Group then the template will appear. I would think however, that the Advanced Users may be able to see both templates given that the higher level permissions would incorporate the lower level permissions.
Hope this helps.