Subscription Service - Workflow error

Hi

When using the subscription service in a workflow I was presented with the following error, I have used the subscription service previously and it worked fine but in this instance it errored. 

PGS-220000 PostgreSQL error: ERROR: duplicate key value violates unique constraint "nmssubscriptionrcp_key"

The workflow is loading a file and checking if they are already subscribed if they aren't they get subscribed.