May I suggest something here ? My proposal is based on what I see as a redondant feature: basic numbering and management of duplicates. You may have noticed that if you uses numbering there can't be any duplicates
There is a need for a simple management of duplicates by default. Some needs an improved format to have the same lenght for all files, and so a need for a true "Always".
The feature of the # in the format can be attached to a set of 3 options in addition to the Start/Step as follows:
Start [ 0 ] (could be number or letter)
Step [ 1 ]
[O] Continuous numbering
[O] Always for duplicates
[X] Added only if needed (default option)
"Continuous numbering" with a format like "<Modified>_#_<Folder>", starting at 1
01/01/2007_1_My Pictures
02/01/2007_2_My Pictures
23/01/2007_3_My Pictures
23/01/2007_4_My Pictures
01/01/2007_5_My Pictures
...
"Always for duplicates" with the same format "<Modified>_#_<Folder>", starting at 1
01/01/2007_1_My Pictures
01/01/2007_2_My Pictures
02/01/2007_1_My Pictures
23/01/2007_1_My Pictures
23/01/2007_2_My Pictures
...
"If needed" with a format like "<Modified>_<Folder>_###", starting at 0:
01/01/2007_My Pictures_000
01/01/2007_My Pictures_001
02/01/2007_My Pictures
23/01/2007_My Pictures_000
23/01/2007_My Pictures_001
...
"If needed" with a format like "<Modified>_<Folder>", starting at 1:
01/01/2007_My Pictures
01/01/2007_My Pictures_1
02/01/2007_My Pictures
23/01/2007_My Pictures
23/01/2007_My Pictures_1
...
This method allows use of a format like "<Modified>##_<Folder>" where pseudo-seconds are generated
Note that the position of # at the end of the format, in the middle or if there is no # at all may be used for automation.