To resolve a conflict between 2 plugins which both work with testimonials, rename custom post type at ‘My Testimonials->General Settings’ from ‘testimonial’ to any other, like ‘mytestimonial’. Then grant to ‘administrator’ role all capabilities under ‘Testimonials’ group. You will restore access to a full ‘My Testimonials’ menu this way.
But as existing testimonials are stored at the database with ‘testimonial’ post type you will not see them at the testimonials list until you replace post type there too. You will need myPhpAdmin or similar SQL tool for this purpose. Execute this command against your database:
update wp_posts set post_type='mytestimonial' where post_type='testimonial';
Do not forget to replace ‘mytestimonial’ to post type ID you selected.