I recently reach the requirements for I stock exclusivity.Normally i don't think its a good idea to go exclusive but i notice that the files that sells very well on i stock don't sell so well on other agency.Its ok if i remove this files from other sites and only use them on i stock or i have to remove all my files even i do not use them on i stock?It is ok to keep to separate sets of images one for i stock exclusivity and one for other sites?

"It is ok to keep to separate sets of images one for i stock exclusivity and one for other sites?"

No.