This is a supplemental article to how to setup your Zapier integration which you can read here: http://support.visible.vc/data-and-integrations/using-zapier-visible
If you wish to have a data point replaced instead of incremented then use the "Create Data Point" selection when setting up your Visible template in Zapier.
The "Create Data Point" option will create or replace a data point for a particular day. E.g. if you were sending "Active Users" to Zapier & Visible every 4 hours then you would want to use "Create Data Point".
E.g. On Jan 1 if you sent 1,500 Active users and then to end the evening on Jan 1 it was 1,750 it would be 1,750 when selecting Create Data Point. If you selected Add Value to Metric then it would be 3,250 (1,500+1750).
If you have transactional data then using "Add Value to Metric" would be the right choice. E.g. New Users. Each time a new user signs up it will add +1 to the metric.