I try to keep a somewhat consistent naming scheme on my HTML templates. I.e. index.html for main, delete.html for delete page and so forth. But the app_directories
The app_loader looks for templates within your applications in order that they are specified in your INSTALLED_APPS. (http://docs.djangoproject.com/en/dev/ref/templates/api/#loader-types).
My suggestion is to preface the name of your template file with the app name to avoid these naming conflicts.
For example, the template dir for app1 would look like:
templates/
app1_index.html
app1_delete.html
app1_add.html
app1_create.html