Thank you for reply.
I can only find the info on FCOM said that
If there is a discrepancy between the raw data position and the FM position:
PRESS the DATA key on the MCDU.
SELECT the POSITION MONITOR page.
SELECT “FREEZE”.
On the other MCDU: Select the GPS MONITOR page.
But when you found the discrepancy situation then press the freeze*. Is that will get the wrong positon？