Upgraded to Grafana 7 but new plugins failed to load

I am using Grafana 7.0.3, platform used Openshift Rhel 7.6
DB used: default(sqlite3). filesystem is mounted to PV.
New plugins added:
- grafana-polystat-panel
- pierosavi-imageit-panel
- agently-flowcharting-panel

log during installation:

installing grafana-polystat-panel @ 1.2.0

from: https://grafana.com/api/plugins/grafana-polystat-panel/versions/1.2.0/download
into: /myapp/grafana/public/app/plugins
Installed grafana-polystat-panel successfully.
Restart grafana after installing plugins.

But after restarting server, new panels are failed to load - getting “Error Loading Plugin”

server log:

t=2020-06-03T22:17:02+0000 lvl=error msg=“Failed to load plugin” logger=plugins error=“Plugin with ID “grafana-polystat-panel” already exists” pluginPath=/myapp/grafana/public/app/plugins/grafana-polystat-panel
… Plugin with ID “grafana-polystat-panel” already exists failed to register plugin:\n

Can some one help on the above issue, basically we are not able to install any plugin, all of them successfully installed but failed to load.

we have also tried to add plugin ID to default.ini config:
allow_loading_unsigned_plugins = grafana-polystat-panel, pierosavi-imageit-panel, agently-flowcharting-panel

I am using Grafana for the first time. Downloaded the latest version 7. It works fine in my personal computer but fails in work PC with the error as mentioned below.
“Error Loading Plugin
Check the server startup logs for more information.
If this plugin was loaded from git, make sure it was compiled.”
So, I believe this could be a browser level setting. Any guidance will be appreciated…