The testing server application is reading the message format defined in the “PosFormat.ini” as the message format parser. You will need to define it the same as you set in the device before the messages are received in order to show the messages correctly in the testing server application.
In the case that you are certain about the connection, please make sure those devices have different device identification numbers as defined using AT$UNID command.
In the testing server application, how can it parse each parameter?