2371266 - Error : "The alternate server name provided is not unique"

SQL Anywhere reports startup error e.g.:

I. 09/09 11:23:52. Starting checkpoint of "esp_prod" (esp_prod.db) at Fri Sep 09 2016 11:23

I. 09/09 11:23:52. Finished checkpoint of "esp_prod" (esp_prod.db) at Fri Sep 09 2016 11:23

I. 09/09 11:23:52. Recovery complete

E. 09/09 11:23:57. The alternate server name provided is not unique

E. 09/09 11:23:57. Error: Database cannot be started -- The alternate server name provided is not unique

I. 09/09 11:23:57. Database "esp_prod" mirroring:  disconnected from partner "esp_prod_mirror_app5"

E. 09/09 11:23:57. Database cannot be started -- The alternate server name provided is not unique

I. 09/09 11:23:59. Database server shutdown due to startup error

SAP SQL Anywhere running in High Availability mode.

KBA , BC-SYB-SQA , SQL Anywhere (on premise, on demand) , BC-SYB-ESP , Sybase ESP (Event Stream Processor) , Problem