Usually it is not possible. When a DA FORM 6 is used the Soldier receives a “1” after their duty is pulled giving them the lowest number on the DA FORM 6.
Now if for some reason only 3 individuals are on the roster, or other special circumstances exist it would be possible to pull back to back duty.
If there is a question about the validity of the duty roster the Soldier can always request to see the DA FORM 6. for more information on this see AR 220-45.
Most issues of this nature are quickly resolved using your chain of command and reviewing the DA FORM 6.
Hope this Helps!