Could there be another <TR.ExchangeTicker> referring to a different RIC?
The best way to have content questions such as this one answered is by contacting Thomson Reuters Helpdesk. Call Thomson Reuters Helpdesk number in your country or use Contact Us capability in Eikon application.
I notice that my brackets disappeared from the question. I am referring to data item name 'TR.ExchangeTicker'. The question therefore should be: is the content of data item name 'TR.ExchangeTicker' unique for a ticker symbol ("RIC")?