Verified on version 5.8.0.13-rc2.20170502165848_0f98658 The message "Deployment {} already exists on this server" is displayed on the dialog box and user can cancel or deploy the archive with different name. Please refer the attached screenshot.
Created attachment 1276540 [details] Screenshot
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2017:1367