use ambiguous_time_f1.nc
use ambiguous_time_f2.nc

list/l=1:20 T2M[d=1], T2M[d=2]
! I do not understand the warning
!  WARNING: Listed variables have ambiguous coordinates on axes: T

! No warning displayed
save/file=tyty.nc/clobber/l=1:20 T2M[d=1], T2M[d=2]