Dual TRN FMS waypoints...
I just want to say that Tarzanboy's theory is quite an interesting one upon further reflection. What are the odds that there is a perfectly suitable emergency diversion straight ahead with identifier "TRN", plus another location with identifier "TRN" back near the Andaman sea where the aircraft seems to have flown to instead for no apparent reason?
I must admit, it seems like an easy mistake to select the wrong TRN on the display when they would both be roughly the same distance from the place of last contact.