duplicate id error in paypal subscriptions

I'm trying to use the paypal_subscription module to allow paid subscriptions to a site. But when someone tries to subscribe, I get the following error:

Duplicate entry 'ABCDEF' for key 1 query: INSERT INTO paypal_payer (payer_id, first_name, last_name, payer_status) VALUES ("ABCDEF", "john", "doe", "verified")

(I removed any identifying information from the query above for security reasons, but the payer_id appeared to be a valid paypal id)

Also, the user was not granted the specified role. I went in and manually added the role, but on the next cron pass the role was automatically removed. I looked at the paypal_payer table, and there is a record with that payer_id; it has a payer_status of verified.

I'm using paypal's subscriptions feature rather than a one-time payment, so that the subscriber will be automatically renewed at the end of the subscription period, if that makes a difference.

Thanks.