Views Result Once

Using this module you are able to restrict results/output from views to be presented once (and only once).

This is useful when generating incremental reports, or sending out subscriptions, and other kind of updates, which you want to be sent only once to users without any duplicates.

How to test:
1) Enable views result once module
2) Go to admin/config/content/views-result-once
3) Select which views you wish to be extended with this functionality.
4) Run views to observe results being presented only once (administrative views "preview" also counts).

I've left additional "sid" column in database table to allow other modules extend this functionality for their own purposes, such as subscription ID towards data managed in some other table (this will allow you executing said subscription only once, preventing duplicate runs).