Krishna,
I'm not sure how LO typically manages localizer privs, but in the
Sugar Labs Pootle instance we generally reserve "Upload with
Overwrite" to language administrators.
The option to grant this specific priv exists in the Language
Administration tab of Poolte (only accessible to Pootle superuser or
language admins) . where the possible options that can be granted to a
Pootle username (individually for a given language) are:
Can change a directory
Can make a suggestion for a translation
Can review translations
Can delete a directory
Can commit to version control
Can add a directory
Can administrate a translation project
Can submit a translation
Can download archives of translation projects
Can overwrite translations on uploading files
Can view a translation project
To make management of privs easier, there are also the "user roles" of:
"nobody" (an unregistered or unlogged-on user)
"default" (a registered and logged-on user)
What you would need to be able to "Upload with Overwrite" is to have
the priv of "Can overwrite translations on uploading files" assigned
to your Pootle username by a Pootle superuser (Rimas?) or the language
administrator for your language.
Hope this helps.
cjl