Separating Invoice Release and Approval

Hello, still slowly working my way through some perceived issues we have with Projects to AR

I would like to know if there is an easy way to separate out Invoice Release and Invoice Approval to ensure that the same person des not perform both tasks?

You can see this on the attached

The same person has performed both activities

The only way I can think to do this would be to create 2 responsibilities

One with the Approve button greyed out

& the second with the Release button greyed out

This would work but is likely to create problems when someone is on leave or on long term sick etc