WordPress Creating Several Duplicate Posts For Every Single Post On My Site

I don’t think either of those query string variables– ‘gid’ or ‘r’– are WordPress native. I just looked in the WP_Query object and can’t find them.

Since you deactivated your plugins, a possibility is that your theme is doing this. Switch to another theme and see if it helps.

Where do you see those URLs anyway?

Also, deactivating the plugin may not remove duplicate posts if they have already been inserted into the database.