Unless you have clearly defined separate roles, titles, career ladders, etc. for the "bug fixers", this isn't a recipe for success. You would end up with an und

Unless you have clearly defined separate roles, titles, career ladders, etc. for the "bug fixers", this isn't a recipe for success. You would end up with an underclass of employees that are unhappy that they don't have the same career opportunities as others in their role, and a bunch of unhappy managers who are given the difficult task of enforcing this division. If you just need someone for narrowly-scoped tasks like fixing specific bugs, it might be better to hire a contractor, so the role expectations can be well-defined and agreed to up front.