Why do we have two contacts for the same email address?

Environment:

Incoming E-mail, Contact auto-create
Oracle B2C Service, All versions

Issue:

We have received two incidents almost at the same time from the same email address and it created two contacts.

Resolution:

One of the features of the techmail utility is parallel processing which allows for multiple messages in a mailbox to be processed at the same time. There is a possible scenario (with a new contact) in which two messages sent at the same time from the same address will generate two separate contact records. Both processes are unable to find the contact in the database (since it did not previously exist) and will therefore create a new record. This may happen occasionally and is an expected behavior.