I am not shy to correct my own statements - obviously I have made a mistake myself...
The wrist watch of the OP is pretty small and the case design (lugs) is the same as on the ref. 2144
As the watch has a center second movement encased in the same case style of 2144 it might deserve a different ref.# maybe 214
5 or other 214
x ?
There is a ref. 214
3 in the data base which has the same case and movement as 2144 but does not have chronometre rating and hence no chronometre inscription on the dial.
Only an extract from the archive will shed some light on this topic and hence we would need at least the movement serial#
I am pretty confident that there is no ref.# in the case back, only a case serial.
Let´s wait and see.