When you say INTG/ACPT regions it's completely site independent specifications.
These are just an environments in a generic Endevor.
If you got quick reference, I recommend you check QW (with that error).
If you don't have..then
Secondly it's good to send this error to you Endevor support team because they are the best people who do maintenance at your site of Endevor product.
The element/module you are trying to move from INTG - ACPT (as per your site) environment already have other vesion which you didn't use for your work.
When ever you add an element to Endevor, it writes the element footprints and stores in Endevor files like MCF (master files). Whenever you try to update some thing on that element, it expects the developer to retrieve from that added environment and after done change it again adds/moves back to same environment which it check the previous foot prints for matching, if not it will through error which you got.