How far have you gone? have you done many tables already? you can set one master table for already-enriched leads.
This way, all your new tables start with a "lookup single/multiple row in another table" to see if this new enrichment is already in the backlog table. then conditionally proceed if it isn't and your rows can end with a "Write to other table" where you write the successful new row into the backlog.
Just thought this up. Dunno how feasible it might be.