"Duplicate Entry Error" Upon App Installation Attempt

I am trying to install a custom app, but am faced with the following error:
frappe.exceptions.DuplicateEntryError: (u'Module Def', u'vcs', IntegrityError(1062, "Duplicate entry 'vcs' for key 'PRIMARY'"))

try to uninstall app,

bench --site site_name uninstall-app appname

or for current site simply run

bench uninstall-app appname

Welcome @vongol

A search of DuplicateEntryError turned up this thread that may provide answers

Error while setup erpnext - #4 by makarand_b

I’m working on that now; but, I keep running into a “connection refused” error regarding redis when I try to uninstall the app.

Same problem. Anybody has solution?