I am not able to open local app using ?dev=true while the app is installed, i need to disable installed app in order to test local version of same app.
FYI: insecure content flag has been already enabled in chrome settings
The issue is not with the local app testing with dev=true (or) allowing insecure content with chrome. The app location has restriction.
Currently, we support only one app in the cti_global_sidebar location. The latest installed app will be taking the precedence.
You can read more about the same here (as a note) - App Locations
However, we do allow more than one app in other placeholders like ticket_sidebar. You can either try to render it in other location for your testing (or) disable installed app temporary.